Rice cultivar CL 181-AR

ABSTRACT

A rice cultivar designated CL 181-AR is disclosed. The invention relates to the seeds of rice cultivar CL 181-AR, to the plants of rice CL 181-AR, to methods for producing a rice plant produced by crossing the cultivar CL 181-AR with itself or another rice variety, and to methods for controlling weeds in the vicinity of plants of rice cultivar CL 181-AR, which comprises increased resistance to acetohydroxyacid synthase-inhibiting herbicides. The invention further relates to hybrid rice seeds and plants produced by crossing the cultivar CL 181-AR with another rice cultivar.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinctive rice cultivar, designated CL 181-AR. All publications cited in this application are herein incorporated by reference.

Rice is an ancient agricultural crop and is today one of the principal food crops of the world. There are two cultivated species of rice: Oryza sativa L., the Asian rice, and O. glaberrima Steud., the African rice. O. sativa L. constitutes virtually all of the world's cultivated rice and is the species grown in the United States. Three major rice producing regions exist in the United States: the Mississippi Delta (Arkansas, Mississippi, northeast Louisiana, southeast Missouri), the Gulf Coast (southwest Louisiana, southeast Texas), and the Central Valleys of California.

Rice is a semi-aquatic crop that benefits from flooded soil conditions during part or all of the growing season. In the United States, rice is grown on flooded soils to optimize grain yields. Heavy clay soils or silt loam soils with hard pan layers about 30 cm below the surface are typical rice-producing soils because they minimize water losses from soil percolation. Rice production in the United States can be broadly categorized as either dry-seeded or water-seeded. In the dry-seeded system, rice is sown into a well-prepared seed bed with a grain drill or by broadcasting the seed and incorporating it with a disk or harrow. Moisture for seed germination is from irrigation or rainfall. Another method of planting by the dry-seeded system is to broadcast the seed by airplane into a flooded field, then promptly drain the water from the field. For the dry-seeded system, when the plants have reached sufficient size (four- to five-leaf stage), a shallow permanent flood of water 5 cm to 16 cm deep is applied to the field for the remainder of the crop season.

In the water-seeded system, rice seed is soaked for 12 to 36 hours to initiate germination, and the seed is broadcast by airplane into a flooded field. The seedlings emerge through a shallow flood, or the water may be drained from the field for a short period of time to enhance seedling establishment. A shallow flood is maintained until the rice approaches maturity. For both the dry-seeded and water-seeded production systems, the fields are drained when the crop is mature, and the rice is harvested 2 to 3 weeks later with large combines. In rice breeding programs, breeders try to employ the production systems predominant in their respective region. Thus, a drill-seeded breeding nursery is used by breeders in a region where rice is drill-seeded and a water-seeded nursery is used in regions where water-seeding is important.

Rice in the United States is classified into three primary market types by grain size, shape, and chemical composition of the endosperm: long-grain, medium-grain and short-grain. Typical U.S. long-grain cultivars cook dry and fluffy when steamed or boiled, whereas medium and short-grain cultivars cook moist and sticky. Long-grain cultivars have been traditionally grown in the southern states and generally receive higher market prices.

Although specific breeding objectives vary somewhat in the different regions, increasing yield is a primary objective in all programs. Grain yield of rice is determined by the number of panicles per unit area, the number of fertile florets per panicle, and grain weight per floret. Increases in any or all of these yield components may provide a mechanism to obtain higher yields. Heritable variation exists for all of these components, and breeders may directly or indirectly select for increases in any of them.

There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The goal is to combine in a single variety an improved combination of desirable traits from the parental germplasm. These important traits may include higher seed yield, resistance to diseases and insects, better stems and roots, tolerance to low temperatures, and better agronomic characteristics or grain quality.

Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F₁ hybrid cultivar, pureline cultivar, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, and recurrent selection, or a combination of these methods.

The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination, and the number of hybrid offspring from each successful cross.

Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).

Promising advanced breeding lines are thoroughly tested and compared to appropriate standards in environments representative of the commercial target area(s) for three or more years. The best lines are candidates for new commercial cultivars; those still deficient in a few traits may be used as parents to produce new populations for further selection.

These processes, which lead to the final step of marketing and distribution, usually take from 8 to 12 years from the time the first cross is made and may rely on the development of improved breeding lines as precursors. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.

A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a single observation is inconclusive, replicated observations provide a better estimate of its genetic worth.

The goal of rice plant breeding is to develop new, unique and superior rice cultivars and hybrids. The breeder initially selects and crosses two or more parental lines, followed by self-pollination and selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selling, and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop the same line, or even very similar lines, having the same rice traits.

Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic and soil conditions, and further selections are then made, during and at the end of the growing season. The cultivars which are developed are unpredictable. This unpredictability is because the breeder's selection occurs in unique environments, with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. The same breeder cannot produce the same cultivar twice by using the exact same original parents and the same selection techniques. This unpredictability results in the expenditure of large amounts of research monies to develop superior new rice cultivars.

The development of new rice cultivars requires the development and selection of rice varieties, the crossing of these varieties and selection of superior crosses. The F₁ seed is produced by manual crosses between selected male-fertile parents or by using male sterility systems. These F₁s are selected for certain single gene traits such as semi-dwarf plant type, pubescence, awns, and apiculus color which indicate that the seed is truly a hybrid. Additional data on parental lines, as well as the phenotype of the F₁, influence the breeder's decision whether to continue with the specific cross.

Pedigree breeding and recurrent selection breeding methods are used to develop cultivars from breeding populations. Breeding programs combine desirable traits from two or more cultivars or various broad-based sources into breeding pools from which cultivars are developed by selfing and selection of desired phenotypes. The new cultivars are evaluated to determine which have commercial potential.

Pedigree breeding is used commonly for the improvement of self-pollinating crops. Two parents which possess favorable, complementary traits are crossed to produce an F₁. An F₂ population is produced by selfing one or several F₁'s. Selection of the best individuals may begin in the F₂ population; then, beginning in the F₃, the best individuals in the best families are selected. Replicated testing of families can begin in the F₄ generation to improve the effectiveness of selection for traits with low heritability. At an advanced stage of inbreeding (i.e., F₆ and F₇), the best lines or mixtures of phenotypically similar lines are tested for potential release as new cultivars.

Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.

Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or inbred line which is the recurrent parent. The source of the trait to be transferred is called the donor parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.

The single-seed descent procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one seed sample to plant the next generation. When the population has been advanced from the F₂ to the desired level of inbreeding, the plants from which lines are derived will each trace to different F₂ individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F₂ plants originally sampled in the population will be represented by a progeny when generation advance is completed.

In a multiple-seed procedure, rice breeders commonly harvest one or more seeds from each plant in a population and thresh them together to form a bulk. Part of the bulk is used to plant the next generation and part is put in reserve. The procedure has been referred to as modified single-seed descent or the pod-bulk technique.

The multiple-seed procedure has been used to save labor at harvest. It is considerably faster to thresh panicles with a machine than to remove one seed from each by hand for the single-seed procedure. The multiple-seed procedure also makes it possible to plant the same number of seeds of a population each generation of inbreeding. Enough seeds are harvested to make up for those plants that did not germinate or produce seed.

Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Allard, 1960; Simmonds, 1979; Sneep, et. al, 1979; Fehr, 1987).

Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer; for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.

Rice, Oryza sativa L., is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop stable, high yielding rice cultivars that are agronomically sound. The reasons for this goal are obviously to maximize the amount of grain produced on the land used and to supply food for both animals and humans. To accomplish this goal, the rice breeder must select and develop rice plants that have the traits that result in superior cultivars.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.

SUMMARY OF THE INVENTION

The following embodiments and aspects thereof are described in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

According to the invention, there is provided a novel rice cultivar designated CL 181-AR. This invention thus relates to the seeds of rice cultivar CL 181-AR, to the plants of rice CL 181-AR, and to methods for producing a rice plant produced by crossing rice CL 181-AR with itself or another rice line.

Thus, any such methods using rice variety CL 181-AR are part of this invention: selling, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using rice variety CL 181-AR as a parent are within the scope of this invention. Advantageously, the rice variety could be used in crosses with other, different, rice plants to produce first generation (F₁) rice hybrid seeds and plants with superior characteristics.

In another aspect, the present invention provides for single gene converted plants of CL 181-AR. The single transferred gene may preferably be a dominant or recessive allele. Preferably, the single transferred gene will confer such traits as herbicide resistance, insect resistance, resistance for bacterial, fungal, or viral disease, male fertility, male sterility, enhanced nutritional quality, and industrial usage. The single gene may be a naturally occurring rice gene or a transgene introduced through genetic engineering techniques.

In another aspect, the present invention provides regenerable cells for use in tissue culture of rice plant CL 181-AR. The tissue culture will preferably be capable of regenerating plants having the physiological and morphological characteristics of the foregoing rice plant, and of regenerating plants having substantially the same genotype as the foregoing rice plant. Preferably, the regenerable cells in such tissue cultures will be embryos, protoplasts, meristematic cells, callus, pollen, leaves, anthers, pistils, root tips, flowers, seeds, panicles, or stems. Still further, the present invention provides rice plants regenerated from the tissue cultures of the invention.

In one aspect, the present invention provides methods for controlling weeds or undesired vegetation in the vicinity of a plant of rice cultivar CL 181-AR. One method comprises applying an effective amount of an acetohydroxyacid synthase (AHAS)-inhibiting herbicide, particularly an imidazolinone herbicide, to the weeds and to a plant of rice cultivar CL 181-AR. Another method comprises contacting a seed of rice cultivar CL 181-AR before sowing and/or after pregermination with an effective amount of an AHAS-inhibiting herbicide, particularly an imidazolinone herbicide. The present invention further provides seeds of rice cultivar CL 181-AR treated with an effective amount of an AHAS-inhibiting herbicide, particularly an imidazolinone herbicide.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by study of the following descriptions.

DEFINITIONS

In the description and tables which follow, a number of terms are used. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:

Alkali Spreading Value. Indicator of gelatinization temperature and an index that measures the extent of disintegration of milled rice kernel in contact with dilute alkali solution. Standard long grains have 3 to 5 Alkali Spreading Value (intermediate gelatinization temperature).

Allele. Allele is any of one or more alternative forms of a gene, all of which relate to one trait or characteristic. In a diploid cell or organism, the two alleles of a given gene occupy corresponding loci on a pair of homologous chromosomes.

Apparent Amylose Percent. The most important grain characteristic that describes cooking behavior in each grain class, or type, i.e., long-, medium- and short-grain. The percentage of the endosperm starch of milled rice that is amylose. Standard long grains contain 20% to 23% amylose. Rexmont type long grains contain 24% to 25% amylose. Short and medium grains contain 16% to 19% amylose. Waxy rice contains 0% amylose. Amylose values will vary over environments.

Backcrossing. Backcrossing is a process in which a breeder repeatedly crosses hybrid progeny back to one of the parents, for example, a first generation hybrid F₁ with one of the parental genotypes of the F₁ hybrid.

Days to 50% heading. Average number of days from emergence to the day when 50% of all panicles are exerted at least partially through the leaf sheath. A measure of maturity.

Essentially all the physiological and morphological characteristics. A plant having essentially all the physiological and morphological characteristics means a plant having the physiological and morphological characteristics of the cultivar, except for the characteristics derived from the converted gene.

Grain Length (L). Length of a rice grain is measured as millimeters.

Grain Width (W). Width of a rice grain is measured as millimeters.

Grain Yield. Grain yield is measured in pounds per acre and at 12.0% moisture. Grain yield of rice is determined by the number of panicles per unit area, the number of fertile florets per panicle, and grain weight per floret.

Harvest Moisture. The percent of moisture of the grain when harvested.

Length/Width (L/W) Ratio. This ratio is determined by dividing the average length (L) by the average width (W).

Lodging Resistance (also called Straw Strength). Lodging is measured as a subjective rating and is percentage of the plant stems leaning or fallen completely to the ground before harvest. Relative scale.

1000 Grain Wt. The weight of 1000 rice grains as measured in grams.

Plant Height. Plant height in centimeters is taken from soil surface to the tip of the extended panicle at harvest.

Peak Viscosity. The maximum viscosity attained during heating when a standardized instrument-specific protocol is applied to a defined rice flour-water slurry.

Trough Viscosity. The minimum viscosity after the peak, normally occurring when the sample starts to cool.

Final Viscosity. Viscosity at the end of the test or cold paste.

Breakdown. The peak viscosity minus the hot paste viscosity.

Setback. Setback 1 is the final viscosity minus trough viscosity. Setback 2 is the final viscosity minus peak viscosity.

RVA Viscosity. Rapid Visco Analyzer is a widely used laboratory instrument to examine paste viscosity, or thickening ability of milled rice during the cooking process.

Hot Paste Viscosity. Viscosity measure of rice flour/water slurry after being heated to 95° C. Lower values indicate softer and stickier cooking types of rice.

Cool Paste Viscosity. Viscosity measure of rice flour/water slurry after being heated to 95° C. and uniformly cooled to 50° C. (American Association of Cereal Chemist). Values less than 200 for cool paste indicate softer cooking types of rice.

Quantitative Trait Loci (QTL). Quantitative trait loci (QTL) refer to genetic loci that control to some degree numerically representable traits that are usually continuously distributed.

Regeneration. Regeneration refers to the development of a plant from tissue culture.

Single Gene Converted (Conversion). Single gene converted (conversion) plant refers to plants which are developed by a plant breeding technique called backcrossing wherein essentially all of the desired morphological and physiological characteristics of a variety are recovered in addition to the single gene transferred into the variety via the backcrossing technique or via genetic engineering.

DETAILED DESCRIPTION OF THE INVENTION

CL 181-AR originated from a cross made at in Crowley, La. in winter 2001. Rice cultivar CL 181-AR is a very high-yielding, short to mid-season, long-grain, Clearfield rice cultivar with maturity similar to rice cultivar ‘CL 171 AR’. Plants of CL 181-AR have erect culms, green erect leaves and glaborus lemma, palea, and leaf blades. The lemma and palea are straw colored and the apiculi are mainly colorless with a few purples at maturity. Kernels of rice cultivar CL 181-AR are similar to size of kernels of ‘Wells.’ Individual milled kernel weights (in milligrams) of rice cultivar CL 181-AR, ‘CL171-AR’, ‘CL161’, ‘Francis’, ‘Wells’, and ‘Cocodrie’ are 18.5, 17.1, 16.4, 17.3, 18.9, and 17.8, respectively, from the Arkansas Rice Performance Trials (ARPT) conducted from 2007 to 2008.

CL 181-AR is a semi-dwarf cultivar which is similar in height to rice cultivar CL 131. On a relative straw strength scale (0=very strong straw, 9=very weak straw), rice cultivars CL 181-AR, ‘Francis’, ‘Wells’, ‘LaGrue’, ‘Drew’, ‘CL161’ and ‘Cocodrie’ rated 2, 4, 3, 5, 6, 4, and 2, respectively.

The rough rice grain yields of rice cultivar CL 181-AR are very similar to rice cultivar ‘Cocodrie’ in the ARPT. In 10 ARPT tests conducted between 2007 to 2008, CL 181-AR, ‘CL171-AR’, ‘CL161’, ‘Francis’, ‘Wells’, and ‘Cocodrie’, averaged yields of 7913, 7610, 7510, 8921, 8820, and 7862 kg ha⁻¹ (120 g kg⁻¹ (12%) moisture), respectively. Milling yields (mg g⁻¹ whole kernel:mg g⁻¹ total milled rice) at 120 mg g⁻¹ moisture from the ARPT conducted from 2007-2008 averaged 570:700, 570:720, 600:710, 570:710, 510:710, and 620:710, for CL 181-AR, ‘CL171-AR’, ‘CL161’, ‘Francis’, ‘Wells’, and ‘Cocodrie’, respectively.

The cultivar has shown uniformity and stability as described in the following variety description information. It has been self-pollinated a sufficient number of generations with careful attention to uniformity of plant type. The variety has been increased with continued observation to enhance uniformity.

Rice cultivar CL 181-AR has the following morphologic and other characteristics (based primarily on data collected in Stuttgart, Ark.).

TABLE 1 VARIETY DESCRIPTION INFORMATION Plant: Grain type: Long Days to maturity (50% heading): 91 days (range is 81-97 days; average from 2007-2008 ARPT) Plant height: 85 cm (range is 74-97 cm; average from 2007-2008 ARPT) Plant color (at booting): green Culm: Angle (degrees from perpendicular after flowering): Erect (<30 degrees) Flag leaf (after heading): Pubescence: Glabrous Leaf angle (after heading): Erect Blade color: Green Panicle: Length: 24.9 cm (range is 20.1-31 cm) Type: Intermediate Exsertion (near maturity): 99% to 100% Axis: Droopy Shattering: Low, 1% to 5% Grain (Spikelet): Awns (after full heading): Absent with a few tip awns at high fertility Apiculus color (at maturity): Mainly straw there may be a few purples at maturity Stigma color: Mainly white to very light purple Lemma and palea color (at maturity): Straw Lemma and palea pubescence: Glabrous Grain (Seed): Seed coat (bran) color: Light-brown Endosperm type: Nonglutinous Scent: Nonscented Shape class (length/width ratio): Paddy: Long 3.63:1 Brown: Long 3.09:1 Milled: Long 3.12:1 Size: 17.9 mg/seed milled rice, 24.2 mg/seed rough rice Starch amylose content: 21-23 g kg⁻¹ Alkali spreading value: 3 to 5 (17 g kg⁻¹ KOH Solution) Gelatinization temperature type: Intermediate (70° C. to 75° C.) Disease Resistance: Rice blast (Magnaporthe oryzae B. Couch = Pyricularia oryzae Cavara): Susceptible Straighthead (physiological disorder): Moderately susceptible Narrow brown leaf spot (Cercospora oryzae Miyake): Moderately susceptible Kernel smut (Tilletia barclayana (Bref.) Sacc. & Syd. in Sacc.): Susceptible Stem rot (Magnaporthe salvinii (Catt.) R. Krause & Webster = Sclerotium oryzae Catt): Susceptible Sheath blight (Thanatephorus cucumeris (A. B. Frank) Donk = Rhizoctonia solani Kühn): Very susceptible False smut (Ustilaginoidea virens (Cooke) Takah.): Susceptible Crown (black) sheath rot (Gaeumannomyces graminis (Sacc.) Arx & D. Olivier): Moderately susceptible Bacterial panicle blight (Burkholderia glumae): Susceptible Herbicide Resistance: Imidazolinones

This invention also is directed to methods for producing a rice plant by crossing a first parent rice plant with a second parent rice plant wherein either the first or second parent rice plant is a rice plant of the line CL 181-AR. Further, both first and second parent rice plants can come from the rice cultivar CL 181-AR. Still further, this invention also is directed to methods for producing a rice cultivar CL 181-AR-derived rice plant by crossing rice cultivar CL 181-AR with a second rice plant and growing the progeny seed, and repeating the crossing and growing steps with the rice cultivar CL 181-AR-derived plant from 0 to 7 times. Thus, any such methods using the rice cultivar CL 181-AR are part of this invention: selling, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using rice cultivar CL 181-AR as a parent are within the scope of this invention, including plants derived from rice cultivar CL 181-AR. Advantageously, the rice cultivar is used in crosses with other, different, rice cultivars to produce first generation (F₁) rice seeds and plants with superior characteristics.

It should be understood that the cultivar can, through routine manipulation of cytoplasmic or other factors, be produced in a male-sterile form. Such embodiments are also contemplated within the scope of the present claims.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which rice plants can be regenerated, plant calli, plant clumps and plant cells that are intact in plants or parts of plants, such as embryos, pollen, ovules, flowers, glumes, panicles, leaves, stems, roots, root tips, anthers, pistils, and the like.

FURTHER EMBODIMENTS OF THE INVENTION

Methods for Controlling Weeds Using the Present Invention

The plants of rice cultivar CL 181-AR have increased tolerance or resistance to AHAS-inhibiting herbicides, particularly imidazolinone herbicides. Thus, the plants of rice cultivar CL 181-AR are herbicide-tolerant or herbicide-resistant rice plants. An “herbicide-tolerant” or a “herbicide-resistant” rice plant is a rice plant that is tolerant or resistant to at least one herbicide at a level that would normally kill, or inhibit the growth of, a normal or wild-type rice plant. For the present invention, the terms “herbicide-tolerant” and “herbicide-resistant” are used interchangeably and are intended to have an equivalent meaning and an equivalent scope. Similarly, the terms “herbicide-tolerance” and “herbicide-resistance” are used interchangeably and are intended to have an equivalent meaning and an equivalent scope. Likewise, the terms “imidazolinone-tolerant” and “imidazolinone-resistant” are used interchangeably and are intended to be of an equivalent meaning and an equivalent scope as the terms “imidazolinone-tolerance” and “imidazolinone-resistance”, respectively.

The plants of rice cultivar CL 181-AR have increased resistance to AHAS-inhibiting herbicides, particularly imidazolinone herbicides, and thus find use in methods for controlling weeds. Accordingly, the present invention provides a method for controlling weeds in the vicinity of a rice plant of the invention. The method comprises applying an effective amount of an herbicide to the weeds and to the rice plant of the present invention.

For the methods of the present invention, the preferred amount or concentration of the herbicide is an “effective amount” or “effective concentration.” “Effective amount” and “effective concentration” is intended to be an amount and concentration, respectively, that is sufficient to kill or inhibit the growth of a similar, wild-type, rice plant, rice plant tissue, rice plant cell, or rice seed, but that said amount does not kill or inhibit as severely the growth of the herbicide-resistant plants, plant tissues, plant cells, and seeds of the present invention. Typically, the effective amount of an herbicide is an amount that is routinely used in agricultural production systems to kill weeds of interest. Such an amount is known to those of ordinary skill in the art.

By “similar, wild-type, plant, plant tissue, plant cell or seed” is intended to be a plant, plant tissue, plant cell, or seed, respectively, that lacks the herbicide-resistance characteristics and/or particular polynucleotide of the invention that are disclosed herein. The use of the term “wild-type” is not, therefore, intended to imply that a plant, plant tissue, plant cell, or other seed lacks recombinant DNA in its genome, and/or does not possess herbicide resistant characteristics that are different from those disclosed herein.

The present invention provides methods for controlling weeds or undesired vegetation in the vicinity of plants of rice cultivar CL 181-AR. The methods involve applying an effective amount of at least one herbicide that interferes with the activity of the AHAS enzyme. Herbicides that are known to interfere with or inhibit the activity of the wild-type AHAS enzyme are known as AHAS-inhibiting herbicides, and include, for example, imidazolinone herbicides, sulfonylurea herbicides, triazolopyrimidine herbicides, pyrimidinyloxybenzoate herbicides, sulfonylamino-carbonyltriazolinone herbicides, and mixtures thereof. Preferably, for the present invention, the AHAS-inhibiting herbicide is an imidazolinone herbicide, or a mixture of two or more imidazolinone herbicides.

For the present invention, the imidazolinone herbicides include, but are not limited to, PURSUIT (imazethapyr), CADRE (imazapic), RAPTOR (imazamox), SCEPTER (imazaquin), ASSERT (imazethabenz), ARSENAL (imazapyr), a derivative of any of the aforementioned herbicides, and a mixture of two or more of the aforementioned herbicides, for example, imazapyr/imazamox (ODYSSEY). More specifically, the imidazolinone herbicide can be selected from, but is not limited to, 2-(4-isopropyl-4-methyl-5-oxo-2-imidiazolin-2-yl)-nicotinic acid, [2-(4-isopropyl)-4-][methyl-5-oxo-2-imidazolin-2-yl)-3-quinolinecarboxylic]acid, [5-ethyl-2-(4-isopropyl-]4-methyl-5-oxo-2-imidazolin-2-yl)-nicotinic acid, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-(methoxymethyl)-nicotinic acid, [2-(4-isopropyl-4-methyl-5-oxo-2-]imidazolin-2-yl)-5-methylnicotinic acid, and a mixture of methyl[6-(4-isopropyl-4-]methyl-5-oxo-2-imidazolin-2-yl)-m-toluate and methyl[2-(4-isopropyl-4-methyl-5-]oxo-2-imidazolin-2-yl)-p-toluate. The use of 5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-nicotinic acid and [2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-]yl)-5-(methoxymethyl)-nicotinic acid is preferred. The use of [2-(4-isopropyl-4-]methyl-5-oxo-2-imidazolin-2-yl)-5-(methoxymethyl)-nicotinic acid is particularly preferred.

For the present invention, the sulfonylurea herbicides include, but are not limited to, chlorsulfuron, metsulfuron methyl, sulfometuron methyl, chlorimuron ethyl, thifensulfuron methyl, tribenuron methyl, bensulfuron methyl, nicosulfuron, ethametsulfuron methyl, rimsulfuron, triflusulfuron methyl, triasulfuron, primisulfuron methyl, cinosulfuron, amidosulfiuon, fluzasulfuron, imazosulfuron, pyrazosulfuron ethyl, halosulfuron, azimsulfuron, cyclosulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron methyl, foramsulfuron, iodosulfuron, oxasulfuron, mesosulfuron, prosulfuron, sulfosulfuron, trifloxysulfuron, tritosulfuron, a derivative of any of the aforementioned herbicides, and a mixture of two or more of the aforementioned herbicides.

The triazolopyrimidine herbicides of the invention include, but are not limited to, cloransulam, diclosulam, florasulam, flumetsulam, metosulam, and penoxsulam.

The pyrimidinyloxybenzoate herbicides of the invention include, but are not limited to, bispyribac, pyrithiobac, pyriminobac, pyribenzoxim and pyriftalid. The sulfonylamino-carbonyltriazolinone herbicides include, but are not limited to, flucarbazone and propoxycarbazone.

It is recognized that pyrimidinyloxybenzoate herbicides are closely related to the pyrimidinylthiobenzoate herbicides and are generalized under the heading of the latter name by the Weed Science Society of America. Accordingly, the herbicides of the present invention further include pyrimidinylthiobenzoate herbicides, including, but not limited to, the pyrimidinyloxybenzoate herbicides described above.

By providing rice plants having increased resistance to herbicides, particularly AHAS-inhibiting herbicides, a wide variety of formulations can be employed for protecting plants from weeds, so as to enhance plant growth and reduce competition for nutrients. An herbicide can be used by itself for pre-emergence, post-emergence, pre-planting and at planting to control weeds in areas surrounding the rice plants described herein, or an imidazolinone herbicide formulation can be used that contains other additives. The herbicide can also be used as a seed treatment. Additives found in an imidazolinone herbicide formulation include other herbicides, detergents, adjuvants, spreading agents, sticking agents, stabilizing agents, or the like. The herbicide formulation can be a wet or dry preparation and can include, but is not limited to, flowable powders, emulsifiable concentrates and liquid concentrates. The herbicide and herbicide formulations can be applied in accordance with conventional methods, for example, by spraying, irrigation, dusting, or the like.

The present invention provides methods that involve the use of at least one AHAS-inhibiting herbicide selected from the group consisting of imidazolinone herbicides, sulfonylurea herbicides, triazolopyrimidine herbicides, pyrimidinyloxybenzoate herbicides, sulfonylamino-carbonyltriazolinone herbicides, and mixtures thereof. In these methods, the AHAS-inhibiting herbicide can be applied by any method known in the art including, but not limited to, seed treatment, soil treatment, and foliar treatment.

Prior to application, the AHAS-inhibiting herbicide can be converted into the customary formulations, for example solutions, emulsions, suspensions, dusts, powders, pastes and granules. The use form depends on the particular intended purpose; in each case, it should ensure a fine and even distribution of the compound according to the invention.

The formulations are prepared in a known manner (see, e.g., for review, U.S. Pat. No. 3,060,084, EP-A 707 445 (for liquid concentrates), Browning, “Agglomeration”, Chemical Engineering, pp. 147-48 (Dec. 4, 1967); Perry's Chemical Engineer's Handbook, 4th Ed., McGraw-Hill, New York, pp. 8-57 (1963), and et seq.; PCT Publication No. WO 91/13546; U.S. Pat. Nos. 4,172,714; 4,144,050; 3,299,566; 3,920,442; 5,180,587; 5,232,701; and 5,208,030; G.B. Patent No. 2,095,558; Klingman, “Weed Control as a Science”, John Wiley and Sons, Inc., New York (1961); Hance et al., Weed Control Handbook, 8th Ed., Blackwell Scientific Publications, Oxford (1989); Mollet, H., Grubemann, A., Formulation technology, Wiley VCH Verlag GmbH, Weinheim, Germany (2001); and D. A. Knowles, Chemistry and Technology of Agrochemical Formulations, Kluwer Academic Publishers (ISBN 0-7514-0443-8), Dordrecht (1998)), for example by extending the active compound with auxiliaries suitable for the formulation of agrochemicals, such as solvents and/or carriers, if desired, emulsifiers, surfactants and dispersants, preservatives, antifoaming agents, anti-freezing agents, for seed treatment formulation, also optionally colorants and/or binders and/or gelling agents.

Examples of suitable solvents are water, aromatic solvents (for example, Solvesso products, xylene), paraffins (for example, mineral oil fractions), alcohols (for example, methanol, butanol, pentanol, benzyl alcohol), ketones (for example, cyclohexanone, gamma-butyrolactone), pyrrolidones (NMP, NOP), acetates (glycol diacetate), glycols, fatty acid dimethylamides, fatty acids and fatty acid esters. In principle, solvent mixtures may also be used.

Examples of suitable carriers are ground natural minerals (for example, kaolins, clays, talc, chalk) and ground synthetic minerals (for example, highly disperse silica, silicates).

Suitable emulsifiers are nonionic and anionic emulsifiers (for example, polyoxyethylene fatty alcohol ethers, alkylsulfonates and arylsulfonates).

Examples of dispersants are lignin-sulfite waste liquors and methylcellulose.

Suitable surfactants used are alkali metal, alkaline earth metal and ammonium salts of lignosulfonic acid, naphthalenesulfonic acid, phenolsulfonic acid, dibutylnaphthalenesulfonic acid, alkylarylsulfonates, alkyl sulfates, alkylsulfonates, fatty alcohol sulfates, fatty acids and sulfated fatty alcohol glycol ethers, furthermore condensates of sulfonated naphthalene and naphthalene derivatives with formaldehyde, condensates of naphthalene or of naphthalenesulfonic acid with phenol and formaldehyde, polyoxyethylene octylphenol ether, ethoxylated isooctylphenol, octylphenol, nonylphenol, alkylphenol polyglycol ethers, tributylphenyl polyglycol ether, tristearylphenyl polyglycol ether, alkylaryl polyether alcohols, alcohol and fatty alcohol ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene alkyl ethers, ethoxylated polyoxypropylene, lauryl alcohol polyglycol ether acetal, sorbitol esters, lignosulfite waste liquors and methylcellulose.

Substances which are suitable for the preparation of directly sprayable solutions, emulsions, pastes or oil dispersions are mineral oil fractions of medium to high boiling point, such as, kerosene or diesel oil, furthermore coal tar oils and oils of vegetable or animal origin, aliphatic, cyclic and aromatic hydrocarbons, for example, toluene, xylene, paraffin, tetrahydronaphthalene, alkylated naphthalenes or their derivatives, methanol, ethanol, propanol, butanol, cyclohexanol, cyclohexanone, isophorone, highly polar solvents, for example, dimethyl sulfoxide, N-methylpyrrolidone or water.

Also anti-freezing agents such as glycerin, ethylene glycol, propylene glycol and bactericides such as can be added to the formulation.

Suitable antifoaming agents are for example antifoaming agents based on silicon or magnesium stearate.

Suitable preservatives are for example Dichlorophen and enzylalkoholhemiformal.

Seed treatment formulations may additionally comprise binders and optionally colorants.

Binders can be added to improve the adhesion of the active materials on the seeds after treatment. Suitable binders are block copolymers EO/PO surfactants but also polyvinylalcohols, polyvinylpyrrolidones, polyacrylates, polymethacrylates, polybutenes, polyisobutylenes, polystyrene, polyethyleneamines, polyethyleneamides, polyethyleneimines (LUPASOL, POLYMIN), polyethers, polyurethans, polyvinylacetate, tylose and copolymers derived from these polymers.

Optionally, colorants can be included in the formulation. Suitable colorants or dyes for seed treatment formulations are Rhodamin B, C.I. Pigment Red 112, C.I. Solvent Red 1, pigment blue 15:4, pigment blue 15:3, pigment blue 15:2, pigment blue 15:1, pigment blue 80, pigment yellow 1, pigment yellow 13, pigment red 112, pigment red 48:2, pigment red 48:1, pigment red 57:1, pigment red 53:1, pigment orange 43, pigment orange 34, pigment orange 5, pigment green 36, pigment green 7, pigment white 6, pigment brown 25, basic violet 10, basic violet 49, acid red 51, acid red 52, acid red 14, acid blue 9, acid yellow 23, basic red 10, basic red 108.

An example of a suitable gelling agent is carrageen (SATIAGEL).

Powders, materials for spreading, and dustable products can be prepared by mixing or concomitantly grinding the active substances with a solid carrier.

Granules, for example, coated granules, impregnated granules and homogeneous granules, can be prepared by binding the active compounds to solid carriers. Examples of solid carriers are mineral earths such as silica gels, silicates, talc, kaolin, attaclay, limestone, lime, chalk, bole, loess, clay, dolomite, diatomaceous earth, calcium sulfate, magnesium sulfate, magnesium oxide, ground synthetic materials, fertilizers, such as, for example, ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas, and products of vegetable origin, such as cereal meal, tree bark meal, wood meal and nutshell meal, cellulose powders and other solid carriers.

In general, the formulations comprise from 0.01% to 95% by weight, preferably from 0.1 to 90% by weight, of the AHAS-inhibiting herbicide. In this case, the AHAS-inhibiting herbicides are employed in a purity of 90% to 100% by weight, preferably 95% to 100% by weight (according to NMR spectrum). For seed treatment purposes, respective formulations can be diluted 2-10 fold leading to concentrations in the ready to use preparations of 0.01% to 60% by weight active compound by weight, preferably 0.1 to 40% by weight.

The AHAS-inhibiting herbicide can be used as such, in the form of their formulations or the use forms prepared therefrom, for example, in the form of directly sprayable solutions, powders, suspensions or dispersions, emulsions, oil dispersions, pastes, dustable products, materials for spreading, or granules, by means of spraying, atomizing, dusting, spreading or pouring. The use forms depend entirely on the intended purposes; they are intended to ensure in each case the finest possible distribution of the AHAS-inhibiting herbicide according to the invention.

Aqueous use forms can be prepared from emulsion concentrates, pastes or wettable powders (sprayable powders, oil dispersions) by adding water. To prepare emulsions, pastes or oil dispersions, the substances, as such or dissolved in an oil or solvent, can be homogenized in water by means of a wetter, tackifier, dispersant or emulsifier. However, it is also possible to prepare concentrates composed of active substance, wetter, tackifier, dispersant or emulsifier and, if appropriate, solvent or oil, and such concentrates are suitable for dilution with water.

The active compound concentrations in the ready-to-use preparations can be varied within relatively wide ranges. In general, they are from 0.0001% to 10%, preferably from 0.01% to 1% per weight.

The AHAS-inhibiting herbicide may also be used successfully in the ultra-low-volume process (ULV), it being possible to apply formulations comprising over 95% by weight of active compound, or even to apply the active compound without additives.

The following are examples of formulations:

1. Products for dilution with water for foliar applications. For seed treatment purposes, such products may be applied to the seed diluted or undiluted.

A. Water-soluble concentrates (SL, LS). Ten parts by weight of the AHAS-inhibiting herbicide are dissolved in 90 parts by weight of water or a water-soluble solvent. As an alternative, wetters or other auxiliaries are added. The AHAS-inhibiting herbicide dissolves upon dilution with water, whereby a formulation with 10% (w/w) of AHAS-inhibiting herbicide is obtained.

B. Dispersible concentrates (DC). Twenty parts by weight of the AHAS-inhibiting herbicide are dissolved in 70 parts by weight of cyclohexanone with addition of 10 parts by weight of a dispersant, for example polyvinylpyrrolidone. Dilution with water gives a dispersion, whereby a formulation with 20% (w/w) of AHAS-inhibiting herbicide is obtained.

C. Emulsifiable concentrates (EC). Fifteen parts by weight of the AHAS-inhibiting herbicide are dissolved in 7 parts by weight of xylene with addition of calcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case 5 parts by weight). Dilution with water gives an emulsion, whereby a formulation with 15% (w/w) of AHAS-inhibiting herbicide is obtained.

D. Emulsions (EW, EO, ES). Twenty-five parts by weight of the AHAS-inhibiting herbicide are dissolved in 35 parts by weight of xylene with addition of calcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case 5 parts by weight). This mixture is introduced into 30 parts by weight of water by means of an emulsifier machine (e.g., Ultraturrax) and made into a homogeneous emulsion. Dilution with water gives an emulsion, whereby a formulation with 25% (w/w) of AHAS-inhibiting herbicide is obtained.

E. Suspensions (SC, OD, FS). In an agitated ball mill, 20 parts by weight of the AHAS-inhibiting herbicide are comminuted with addition of 10 parts by weight of dispersants, wetters and 70 parts by weight of water or of an organic solvent to give a fine AHAS-inhibiting herbicide suspension. Dilution with water gives a stable suspension of the AHAS-inhibiting herbicide, whereby a formulation with 20% (w/w) of AHAS-inhibiting herbicide is obtained.

F. Water-dispersible granules and water-soluble granules (WG, SG). Fifty parts by weight of the AHAS-inhibiting herbicide are ground finely with addition of 50 parts by weight of dispersants and wetters and made as water-dispersible or water-soluble granules by means of technical appliances (for example, extrusion, spray tower, fluidized bed). Dilution with water gives a stable dispersion or solution of the AHAS-inhibiting herbicide, whereby a formulation with 50% (w/w) of AHAS-inhibiting herbicide is obtained.

G. Water-dispersible powders and water-soluble powders (WP, SP, SS, WS). Seventy-five parts by weight of the AHAS-inhibiting herbicide are ground in a rotor-stator mill with addition of 25 parts by weight of dispersants, wetters and silica gel. Dilution with water gives a stable dispersion or solution of the AHAS-inhibiting herbicide, whereby a formulation with 75% (w/w) of AHAS-inhibiting herbicide is obtained.

H. Gel-Formulation (GF). In an agitated ball mill, 20 parts by weight of the AHAS-inhibiting herbicide are comminuted with addition of 10 parts by weight of dispersants, 1 part by weight of a gelling agent wetters and 70 parts by weight of water or of an organic solvent to give a fine AHAS-inhibiting herbicide suspension. Dilution with water gives a stable suspension of the AHAS-inhibiting herbicide, whereby a formulation with 20% (w/w) of AHAS-inhibiting herbicide is obtained. This gel formulation is suitable for use as a seed treatment.

2. Products to be applied undiluted for foliar applications. For seed treatment purposes, such products may be applied to the seed diluted.

A. Dustable powders (DP, DS). Five parts by weight of the AHAS-inhibiting herbicide are ground finely and mixed intimately with 95 parts by weight of finely divided kaolin. This gives a dustable product having 5% (w/w) of AHAS-inhibiting herbicide.

B. Granules (GR, FG, GG, MG). One-half part by weight of the AHAS-inhibiting herbicide is ground finely and associated with 95.5 parts by weight of carriers, whereby a formulation with 0.5% (w/w) of AHAS-inhibiting herbicide is obtained. Current methods are extrusion, spray-drying or the fluidized bed. This gives granules to be applied undiluted for foliar use.

Conventional seed treatment formulations include, for example, flowable concentrates FS, solutions LS, powders for dry treatment DS, water dispersible powders for slurry treatment WS, water-soluble powders SS and emulsion ES and EC and gel formulation GF. These formulations can be applied to the seed diluted or undiluted. Application to the seeds is carried out before sowing, either directly on the seeds.

In a preferred embodiment a FS formulation is used for seed treatment. Typically, a FS formulation may comprise 1-800 g/l of active ingredient, 1-200 g/l Surfactant, 0 to 200 g/l antifreezing agent, 0 to 400 g/l of binder, 0 to 200 g/l of a pigment and up to 1 liter of a solvent, preferably water.

For seed treatment, seeds of the rice plants of the present invention are treated with herbicides, preferably herbicides selected from the group consisting of AHAS-inhibiting herbicides, such as, amidosulfuron, azimsulfuron, bensulfuron, chlorimuron, chlorsulfuron, cinosulfuron, cyclosulfamuron, ethametsulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron, foramsulfuron, halosulfuron, imazosulfuron, iodosulfuron, mesosulfuron, metsulfuron, nicosulfuron, oxasulfuron, primisulfuron, prosulfuron, pyrazosulfuron, rimsulfuron, sulfometuron, sulfosulfuron, thifensulfuron, triasulfuron, tribenuron, trifloxysulfuron, triflusulfuron, tritosulfuron, imazamethabenz, imazamox, imazapic, imazapyr, imazaquin, imazethapyr, cloransulam, diclosulam, florasulam, flumetsulam, metosulam, penoxsulam, bispyribac, pyriminobac, propoxycarbazone, flucarbazone, pyribenzoxim, pyriftalid, pyrithiobac, and mixtures thereof, or with a formulation comprising an AHAS-inhibiting herbicide.

The term seed treatment comprises all suitable seed treatment techniques known in the art, such as, seed dressing, seed coating, seed dusting, seed soaking, and seed pelleting.

In accordance with one variant of the present invention, a further subject of the invention is a method of treating soil by the application, in particular into the seed drill: either of a granular formulation containing the AHAS-inhibiting herbicide as a composition/formulation (e.g., a granular formulation, with optionally one or more solid or liquid, agriculturally acceptable carriers and/or optionally with one or more agriculturally acceptable surfactants.

The present invention also comprises seeds coated with or containing with a seed treatment formulation comprising at least one AHAS-inhibiting herbicide selected from the group consisting of amidosulfuron, azimsulfuron, bensulfuron, chlorimuron, chlorsulfuron, cinosulfuron, cyclosulfamuron, ethametsulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron, foramsulfuron, halosulfuron, imazosulfuron, iodosulfuron, mesosulfuron, metsulfuron, nicosulfuron, oxasulfuron, primisulfuron, prosulfuron, pyrazosulfuron, rimsulfuron, sulfometuron, sulfosulfuron, thifensulfuron, triasulfuron, tribenuron, trifloxysulfuron, triflusulfuron, tritosulfuron, imazamethabenz, imazamox, imazapic, imazapyr, imazaquin, imazethapyr, cloransulam, diclosulam, florasulam, flumetsulam, metosulam, penoxsulam, bispyribac, pyriminobac, propoxycarbazone, flucarbazone, pyribenzoxim, pyriftalid, and pyrithiobac.

The term seed embraces seeds and plant propagules of all kinds including, but not limited to, true seeds, seed pieces, suckers, corms, bulbs, fruit, tubers, grains, cuttings, cut shoots and the like and means in a preferred embodiment true seeds.

The term “coated with and/or containing” generally signifies that the active ingredient is for the most part on the surface of the propagation product at the time of application, although a greater or lesser part of the ingredient may penetrate into the propagation product, depending on the method of application. When the said propagation product is (re)planted, it may absorb the active ingredient.

The seed treatment application with the AHAS-inhibiting herbicide or with a formulation comprising the AHAS-inhibiting herbicide is carried out by spraying or dusting the seeds before sowing of the plants and before emergence of the plants.

In the treatment of seeds, the corresponding formulations are applied by treating the seeds with an effective amount of the AHAS-inhibiting herbicide or a formulation comprising the AHAS-inhibiting herbicide. Herein, the application rates are generally from 0.1 g to 10 kg of the a.i. (or of the mixture of a.i. or of the formulation) per 100 kg of seed, preferably from 1 g to 5 kg per 100 kg of seed, in particular from 1 g to 2.5 kg per 100 kg of seed.

The present invention provides a method for combating undesired vegetation or controlling weeds comprising contacting the seeds of the rice plants according to the present invention before sowing and/or after pre-germination with an AHAS-inhibiting herbicide. The method can further comprise sowing the seeds, for example, in soil in a field or in a potting medium in greenhouse. The method finds particular use in combating undesired vegetation or controlling weeds in the immediate vicinity of the seed.

The control of undesired vegetation is understood as meaning the killing of weeds and/or otherwise retarding or inhibiting the normal growth of the weeds. Weeds, in the broadest sense, are understood as meaning all those plants which grow in locations where they are undesired.

The weeds may include, for example, dicotyledonous and monocotyledonous weeds. Dicotyledonous weeds include, but are not limited to, weeds of the genera: Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio, Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Rotala, Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeopsis, Papaver, Centaurea, Trifolium, Ranunculus, and Taraxacum. Monocotyledonous weeds include, but are not limited to, weeds of the genera: Echinochloa, Setaria, Panicum, Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus, Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristyslis, Sagittaria, Eleocharis, Scirpus, Paspalum, Ischaemum, Sphenoclea, Dactyloctenium, Agrostis, Alopecurus, and Apera.

In addition, the weeds of the present invention can include, for example, crop plants that are growing in an undesired location. For example, a volunteer soybean plant that is in a field that predominantly comprises rice plants can be considered a weed, if the soybean plant is undesired in the field of rice plants. Another example of a weed of the present invention is red rice which is the same species as cultivated rice.

Transformation Techniques:

With the advent of molecular biological techniques that have allowed the isolation and characterization of genes that encode specific protein products, scientists in the field of plant biology developed a strong interest in engineering the genome of plants to contain and express foreign genes, or additional, or modified versions of native, or endogenous, genes (perhaps driven by different promoters) in order to alter the traits of a plant in a specific manner. Such foreign additional and/or modified genes are referred to herein collectively as “transgenes.” Over the last fifteen to twenty years, several methods for producing transgenic plants have been developed, and the present invention, in particular embodiments, also relates to transformed versions of the claimed cultivar.

Culture for expressing desired structural genes and cultured cells are known in the art. Also as known in the art, rice is transformable and regenerable such that whole plants containing and expressing desired genes under regulatory control may be obtained. General descriptions of plant expression vectors and reporter genes and transformation protocols can be found in Gruber, et al., “Vectors for Plant Transformation,” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 89-119 (1993)). Moreover GUS expression vectors and GUS gene cassettes are available from Clone Tech Laboratories, Inc. (Palo Alto, Calif.), while luciferase expression vectors and luciferase gene cassettes are available from Pro Mega Corp. (Madison, Wis.). General methods of culturing plant tissues are provided for example by Miki, et al., “Procedures for Introducing Foreign DNA into Plants” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 67-88 (1993)); and by Phillips, et al., “Cell-Tissue Culture and In-Vitro Manipulation” in Corn & Corn Improvement, 3rd Edition, Sprague, et al., (Eds., pp. 345 387, American Society of Agronomy Inc. (1988)). Methods of introducing expression vectors into plant tissue include the direct infection or co-cultivation of plant cells with Agrobacterium tumefaciens, described for example by Horsch, et al., Science, 227:1229 (1985). Descriptions of Agrobacterium vector systems and methods for Agrobacterium-mediated gene transfer are provided by Gruber, et al., supra.

Useful methods include but are not limited to expression vectors introduced into plant tissues using a direct gene transfer method such as microprojectile-mediated delivery, DNA injection, electroporation and the like. More preferably expression vectors are introduced into plant tissues using a microprojectile media delivery system with a biolistic device or using Agrobacterium-mediated transformation. Transformant plants obtained with the protoplasm of the invention are intended to be within the scope of this invention.

Plant transformation involves the construction of an expression vector which will function in plant cells. Such a vector comprises DNA comprising a gene under control of or operatively linked to a regulatory element (for example, a promoter). The expression vector may contain one or more such operably linked gene/regulatory element combinations. The vector(s) may be in the form of a plasmid, and can be used alone or in combination with other plasmids, to provide transformed rice plants, using transformation methods as described below to incorporate transgenes into the genetic material of the rice plant(s).

Expression Vectors for Transformation: Marker Genes

Expression vectors include at least one genetic marker, operably linked to a regulatory element (a promoter, for example) that allows transformed cells containing the marker to be either recovered by negative selection, i.e., inhibiting growth of cells that do not contain the selectable marker gene, or by positive selection, i.e., screening for the product encoded by the genetic marker. Many commonly used selectable marker genes for plant transformation are well known in the transformation arts, and include, for example, genes that code for enzymes that metabolically detoxify a selective chemical agent which may be an antibiotic or an herbicide, or genes that encode an altered target which is insensitive to the inhibitor. A few positive selection methods are also known in the art.

One commonly used selectable marker gene for plant transformation is the neomycin phosphotransferase II (nptII) gene, isolated from transposon Tn5, which when placed under the control of plant regulatory signals confers resistance to kanamycin. Fraley, et al., Proc. Natl. Acad. Sci. U.S.A., 80:4803 (1983). Another commonly used selectable marker gene is the hygromycin phosphotransferase gene which confers resistance to the antibiotic hygromycin. Vanden Elzen, et al., Plant Mol. Biol., 5:299 (1985).

Additional selectable marker genes of bacterial origin that confer resistance to antibiotics include gentamycin acetyl transferase, streptomycin phosphotransferase, and aminoglycoside-3′-adenyl transferase, the bleomycin resistance determinant. Hayford, et al., Plant Physiol., 86:1216 (1988); Jones, et al., Mol. Gen. Genet., 210:86 (1987); Svab, et al., Plant Mol. Biol., 14:197 (1990); Hille, et al., Plant Mol. Biol., 7:171 (1986). Other selectable marker genes confer resistance to herbicides such as glyphosate, glufosinate or bromoxynil. Comai, et al., Nature, 317:741-744 (1985); Gordon-Kamm, et al., Plant Cell, 2:603-618 (1990); and Stalker, et al., Science, 242:419-423 (1988).

Selectable marker genes for plant transformation not of bacterial origin include, for example, mouse dihydrofolate reductase, plant 5-enolpyruvylshikimate-3-phosphate synthase, and plant acetolactate synthase. Eichholtz, et al., Somatic Cell Mol. Genet., 13:67 (1987); Shah, et al., Science, 233:478 (1986); Charest, et al., Plant Cell Rep., 8:643 (1990).

Another class of marker genes for plant transformation requires screening of presumptively transformed plant cells rather than direct genetic selection of transformed cells for resistance to a toxic substance such as an antibiotic. These genes are particularly useful to quantify or visualize the spatial pattern of expression of a gene in specific tissues and are frequently referred to as reporter genes because they can be fused to a gene or gene regulatory sequence for the investigation of gene expression. Commonly used genes for screening presumptively transformed cells include β-glucuronidase (GUS, β-galactosidase, luciferase and chloramphenicol acetyltransferase. Jefferson, R. A., Plant Mol. Biol. Rep., 5:387 (1987); Teeri, et al., EMBO J., 8:343 (1989); Koncz, et al., Proc. Natl. Acad. Sci. U.S.A., 84:131 (1987); DeBlock, et al., EMBO J., 3:1681 (1984). Another approach to the identification of relatively rare transformation events has been use of a gene that encodes a dominant constitutive regulator of the Zea mays anthocyanin pigmentation pathway. Ludwig, et al., Science, 247:449 (1990).

In vivo methods for visualizing GUS activity that do not require destruction of plant tissue are available. Molecular Probes Publication 2908, IMAGENE GREEN, pp. 1-4 (1993) and Naleway, et al., J. Cell Biol., 115:151a (1991). However, these in vivo methods for visualizing GUS activity have not proven useful for recovery of transformed cells because of low sensitivity, high fluorescent backgrounds and limitations associated with the use of luciferase genes as selectable markers.

More recently, a gene encoding Green Fluorescent Protein (GFP) has been utilized as a marker for gene expression in prokaryotic and eukaryotic cells. Chalfie, et al., Science, 263:802 (1994). GFP and mutants of GFP may be used as screenable markers.

Expression Vectors for Transformation: Promoters

Genes included in expression vectors must be driven by nucleotide sequence comprising a regulatory element, for example, a promoter. Several types of promoters are now well known in the transformation arts, as are other regulatory elements that can be used alone or in combination with promoters.

As used herein, “promoter” includes reference to a region of DNA upstream from the start of transcription and involved in recognition and binding of RNA polymerase and other proteins to initiate transcription. A “plant promoter” is a promoter capable of initiating transcription in plant cells. Examples of promoters under developmental control include promoters that preferentially initiate transcription in certain tissues, such as leaves, roots, seeds, fibers, xylem vessels, tracheids, or sclerenchyma. Such promoters are referred to as “tissue-preferred.” Promoters which initiate transcription only in certain tissue are referred to as “tissue-specific.” A “cell type” specific promoter primarily drives expression in certain cell types in one or more organs, for example, vascular cells in roots or leaves. An “inducible” promoter is a promoter which is under environmental control. Examples of environmental conditions that may effect transcription by inducible promoters include anaerobic conditions or the presence of light. Tissue-specific, tissue-preferred, cell type specific, and inducible promoters constitute the class of “non-constitutive” promoters. A “constitutive” promoter is a promoter which is active under most environmental conditions.

A. Inducible Promoters—An inducible promoter is operably linked to a gene for expression in rice. Optionally, the inducible promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in rice. With an inducible promoter the rate of transcription increases in response to an inducing agent.

Any inducible promoter can be used in the instant invention. See, Ward, et al., Plant Mol. Biol., 22:361-366 (1993). Exemplary inducible promoters include, but are not limited to, that from the ACEI system which responds to copper (Melt, et al., PNAS, 90:4567-4571 (1993)); In2 gene from maize which responds to benzenesulfonamide herbicide safeners (Hershey, et al., Mol. Gen. Genetics, 227:229-237 (1991) and Gatz, et al., Mol. Gen. Genetics, 243:32-38 (1994)) or Tet repressor from Tn10 (Gatz, et al., Mol. Gen. Genetics, 227:229-237 (1991)). A particularly preferred inducible promoter is a promoter that responds to an inducing agent to which plants do not normally respond. An exemplary inducible promoter is the inducible promoter from a steroid hormone gene, the transcriptional activity of which is induced by a glucocorticosteroid hormone (Schena, et al., Proc. Natl. Acad. Sci. U.S.A., 88:0421 (1991)).

B. Constitutive Promoters—A constitutive promoter is operably linked to a gene for expression in rice or the constitutive promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in rice.

Many different constitutive promoters can be utilized in the instant invention. Exemplary constitutive promoters include, but are not limited to, the promoters from plant viruses such as the 35S promoter from CaMV (Odell, et al., Nature, 313:810-812 (1985)) and the promoters from such genes as rice actin (McElroy, et al., Plant Cell, 2:163-171 (1990)); ubiquitin (Christensen, et al., Plant Mol. Biol., 12:619-632 (1989) and Christensen, et al., Plant Mol. Biol., 18:675-689 (1992)); pEMU (Last, et al., Theor. Appl. Genet., 81:581-588 (1991)); MAS (Velten, et al., EMBO J., 3:2723-2730 (1984)); and maize H3 histone (Lepetit, et al., Mol. Gen. Genetics, 231:276-285 (1992) and Atanassova, et al., Plant Journal 2 (3): 291-300 (1992)).

The ALS promoter, Xba1/Nco1 fragment 5′ to the Brassica napus ALS3 structural gene (or a nucleotide sequence similarity to said Xba1/Nco1 fragment), represents a particularly useful constitutive promoter. See, PCT Appl. No. WO 96/30530.

C. Tissue-specific or Tissue-preferred Promoters—A tissue-specific promoter is operably linked to a gene for expression in rice. Optionally, the tissue-specific promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in rice. Plants transformed with a gene of interest operably linked to a tissue-specific promoter produce the protein product of the transgene exclusively, or preferentially, in a specific tissue.

Any tissue-specific or tissue-preferred promoter can be utilized in the instant invention. Exemplary tissue-specific or tissue-preferred promoters include, but are not limited to, a root-preferred promoter, such as that from the phaseolin gene (Murai, et al., Science, 23:476-482 (1983) and Sengupta-Gopalan, et al., Proc. Natl. Acad. Sci. U.S.A., 82:3320-3324 (1985)); a leaf-specific and light-induced promoter such as that from cab or rubisco (Simpson, et al., EMBO J., 4(11):2723-2729 (1985) and Timko, et al., Nature, 318:579-582 (1985)); an anther-specific promoter such as that from LAT52 (Twell, et al., Mol. Gen. Genetics, 217:240-245 (1989)); a pollen-specific promoter such as that from Zm13 (Guerrero, et al., Mol. Gen. Genetics, 244:161-168 (1993)) or a microspore-preferred promoter such as that from apg (Twell, et al., Sex. Plant Reprod., 6:217-224 (1993)).

Signal Sequences for Targeting Proteins to Sub-Cellular Compartments

Transport of protein produced by transgenes to a subcellular compartment such as the chloroplast, vacuole, peroxisome, glyoxysome, cell wall, or mitochondrion, or for secretion into the apoplast, is accomplished by means of operably linking the nucleotide sequence encoding a signal sequence to the 5′ and/or 3′ region of a gene encoding the protein of interest. Targeting sequences at the 5′ and/or 3′ end of the structural gene may determine, during protein synthesis and processing, where the encoded protein is ultimately compartmentalized.

The presence of a signal sequence directs a polypeptide to either an intracellular organelle or subcellular compartment or for secretion to the apoplast. Many signal sequences are known in the art. See, for example, Becker, et al., Plant Mol. Biol., 20:49 (1992); Close, P. S., Master's Thesis, Iowa State University (1993); Knox, C., et al., Plant Mol. Biol., 9:3-17 (1987); Lerner, et al., Plant Physiol., 91:124-129 (1989); Fontes, et al., Plant Cell, 3:483-496 (1991); Matsuoka, et al., Proc. Natl. Acad. Sci., 88:834 (1991); Gould, et al., J. Cell. Biol., 108:1657 (1989); Creissen, et al., Plant J., 2:129 (1991); Kalderon, et al., Cell, 39:499-509 (1984); Steifel, et al., Plant Cell, 2:785-793 (1990).

Foreign Protein Genes and Agronomic Genes

With transgenic plants according to the present invention, a foreign protein can be produced in commercial quantities. Thus, techniques for the selection and propagation of transformed plants, which are well understood in the art, yield a plurality of transgenic plants which are harvested in a conventional manner, and a foreign protein then can be extracted from a tissue of interest or from total biomass. Protein extraction from plant biomass can be accomplished by known methods which are discussed, for example, by Heney and Orr, Anal. Biochem., 114:92-6 (1981).

According to a preferred embodiment, the transgenic plant provided for commercial production of foreign protein is rice. In another preferred embodiment, the biomass of interest is seed. For the relatively small number of transgenic plants that show higher levels of expression, a genetic map can be generated, primarily via conventional RFLP, PCR, and SSR analysis, which identifies the approximate chromosomal location of the integrated DNA molecule. For exemplary methodologies in this regard, see Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 269-284 (1993)). Map information concerning chromosomal location is useful for proprietary protection of a subject transgenic plant. If unauthorized propagation is undertaken and crosses made with other germplasm, the map of the integration region can be compared to similar maps for suspect plants, to determine if the latter have a common parentage with the subject plant. Map comparisons would involve hybridizations, RFLP, PCR, SSR, and sequencing, all of which are conventional techniques.

Through the transformation of rice, the expression of genes can be altered to enhance disease resistance, insect resistance, herbicide resistance, agronomic quality and other traits. Transformation can also be used to insert DNA sequences which control or help control male-sterility. DNA sequences native to rice as well as non-native DNA sequences can be transformed into rice and used to alter levels of native or non-native proteins. Various promoters, targeting sequences, enhancing sequences, and other DNA sequences can be inserted into the genome for the purpose of altering the expression of proteins. Reduction of the activity of specific genes (also known as gene silencing, or gene suppression) is desirable for several aspects of genetic engineering in plants.

Many techniques for gene silencing are well-known to one of skill in the art, including, but not limited to, knock-outs (such as by insertion of a transposable element such as mu (Vicki Chandler, The Maize Handbook, ch. 118, Springer-Verlag (1994)) or other genetic elements such as a FRT, Lox, or other site specific integration site, antisense technology (see, e.g., Sheehy, et al., PNAS USA, 85:8805-8809 (1988); and U.S. Pat. Nos. 5,107,065; 5,453,566; and 5,759,829); co-suppression (e.g., Taylor, Plant Cell, 9:1245 (1997); Jorgensen, Trends Biotech., 8(12):340-344 (1990); Flavell, PNAS USA, 91:3490-3496 (1994); Finnegan, et al., Bio/Technology, 12: 883-888 (1994); and Neuhuber, et al., Mol. Gen. Genet., 244:230-241 (1994)); RNA interference (Napoli, et al., Plant Cell, 2:279-289 (1990); U.S. Pat. No. 5,034,323; Sharp, Genes Dev., 13:139-141 (1999); Zamore, et al., Cell, 101:25-33 (2000); and Montgomery, et al., PNAS USA, 95:15502-15507 (1998)); virus-induced gene silencing (Burton, et al., Plant Cell, 12:691-705 (2000); and Baulcombe, Curr. Op. Plant Bio., 2:109-113 (1999)); target-RNA-specific ribozymes (Haseloff, et al., Nature, 334: 585-591 (1988)); hairpin structures (Smith, et al., Nature, 407:319-320 (2000); WO 99/53050; and WO 98/53083); MicroRNA (Aukerman & Sakai, Plant Cell, 15:2730-2741 (2003)); ribozymes (Steinecke, et al., EMBO J., 11:1525 (1992); and Perriman, et al., Antisense Res. Dev., 3:253 (1993)); oligonucleotide mediated targeted modification (e.g., PCT Publication Nos. WO 03/076574 and WO 99/25853); Zn-finger targeted molecules (e.g., PCT Publication Nos. WO 01/52620; WO 03/048345; and WO 00/42219); and other methods or combinations of the above methods known to those of skill in the art.

Likewise, by means of the present invention, agronomic genes can be expressed in transformed plants. More particularly, plants can be genetically engineered to express various phenotypes of agronomic interest. Exemplary genes implicated in this regard include, but are not limited to, those categorized below:

1. Genes that Confer Resistance to Pests or Disease and that Encode:

A. Plant disease resistance genes. Plant defenses are often activated by specific interaction between the product of a disease resistance gene (R) in the plant and the product of a corresponding avirulence (Avr) gene in the pathogen. A plant cultivar can be transformed with cloned resistance gene to engineer plants that are resistant to specific pathogen strains. See, for example, Jones, et al., Science, 266:789 (1994) (cloning of the tomato Cf-9 gene for resistance to Cladosporium fulvum); Martin, et al., Science, 262:1432 (1993) (tomato Pto gene for resistance to Pseudomonas syringae pv. tomato encodes a protein kinase); Mindrinos, et al., Cell, 78:1089 (1994) (Arabidopsis RSP2 gene for resistance to Pseudomonas syringae); McDowell & Woffenden, Trends Biotechnol., 21(4): 178-83 (2003); and Toyoda, et al., Transgenic Res., 11 (6):567-82 (2002).

B. A Bacillus thuringiensis protein, a derivative thereof or a synthetic polypeptide modeled thereon. See, for example, Geiser, et al., Gene, 48:109 (1986), who disclose the cloning and nucleotide sequence of a Bt δ-endotoxin gene. Moreover, DNA molecules encoding δ-endotoxin genes can be purchased from American Type Culture Collection, Manassas, Va., for example, under ATCC Accession Nos. 40098, 67136, 31995, and 31998.

C. A lectin. See, for example, the disclosure by Van Damme, et al., Plant Molec. Biol., 24:25 (1994), who disclose the nucleotide sequences of several Clivia miniata mannose-binding lectin genes.

D. A vitamin-binding protein such as avidin. See, PCT Appl. No. US 93/06487. The application teaches the use of avidin and avidin homologues as larvicides against insect pests.

E. An enzyme inhibitor, for example, a protease or proteinase inhibitor or an amylase inhibitor. See, for example, Abe, et al., J. Biol. Chem., 262:16793 (1987) (nucleotide sequence of rice cysteine proteinase inhibitor); Huub, et al., Plant Molec. Biol., 21:985 (1993) (nucleotide sequence of cDNA encoding tobacco proteinase inhibitor I); Sumitani, et al., Biosci. Biotech. Biochem., 57:1243 (1993) (nucleotide sequence of Streptomyces nitrosporeus α-amylase inhibitor).

F. An insect-specific hormone or pheromone such as an ecdysteroid and juvenile hormone, a variant thereof, a mimetic based thereon, or an antagonist or agonist thereof. See, for example, the disclosure by Hammock, et al., Nature, 344:458 (1990), of baculovirus expression of cloned juvenile hormone esterase, an inactivator of juvenile hormone.

G. An insect-specific peptide or neuropeptide which, upon expression, disrupts the physiology of the affected pest. For example, see the disclosures of Regan, J. Biol. Chem., 269:9 (1994) (expression cloning yields DNA coding for insect diuretic hormone receptor), and Pratt, et al., Biochem. Biophys. Res. Comm., 163:1243 (1989) (an allostatin is identified in Diploptera puntata). See also, U.S. Pat. No. 5,266,317 to Tomalski, et al., who disclose genes encoding insect-specific, paralytic neurotoxins.

H. An insect-specific venom produced in nature by a snake, a wasp, etc. For example, see Pang, et al., Gene, 116:165 (1992), for disclosure of heterologous expression in plants of a gene coding for a scorpion insectotoxic peptide.

I. An enzyme responsible for a hyper-accumulation of a monoterpene, a sesquiterpene, a steroid, a hydroxamic acid, a phenylpropanoid derivative or another non-protein molecule with insecticidal activity.

J. An enzyme involved in the modification, including the post-translational modification, of a biologically active molecule; for example, a glycolytic enzyme, a proteolytic enzyme, a lipolytic enzyme, a nuclease, a cyclase, a transaminase, an esterase, a hydrolase, a phosphatase, a kinase, a phosphorylase, a polymerase, an elastase, a chitinase, and a glucanase, whether natural or synthetic. See, PCT Publication No. WO 93/02197 in the name of Scott, et al., which discloses the nucleotide sequence of a callase gene. DNA molecules which contain chitinase-encoding sequences can be obtained, for example, from the ATCC under Accession Nos. 39637 and 67152. See also, Kramer, et al., Insect Biochem. Molec. Biol., 23:691 (1993), who teach the nucleotide sequence of a cDNA encoding tobacco hornworm chitinase, and Kawalleck, et al., Plant Molec. Biol., 21:673 (1993), who provide the nucleotide sequence of the parsley ubi4-2 polyubiquitin gene.

K. A molecule that stimulates signal transduction. For example, see the disclosure by Botella, et al., Plant Molec. Biol., 24:757 (1994), of nucleotide sequences for mung bean calmodulin cDNA clones, and Griess, et al., Plant Physiol., 104:1467 (1994), who provide the nucleotide sequence of a maize calmodulin cDNA clone.

L. A hydrophobic moment peptide. See, PCT Publication No. WO 95/16776 (disclosure of peptide derivatives of Tachyplesin which inhibit fungal plant pathogens) and PCT Publication No. WO 95/18855 (teaches synthetic antimicrobial peptides that confer disease resistance), the respective contents of which are hereby incorporated by reference.

M. A membrane permease, a channel former or a channel blocker. For example, see the disclosure of Jaynes, et al., Plant Sci, 89:43 (1993), of heterologous expression of a cecropin-β, lytic peptide analog to render transgenic tobacco plants resistant to Pseudomonas solanacearum.

N. A viral-invasive protein or a complex toxin derived therefrom. For example, the accumulation of viral coat proteins in transformed plant cells imparts resistance to viral infection and/or disease development effected by the virus from which the coat protein gene is derived, as well as by related viruses. See, Beachy, et al., Ann. Rev. Phytopathol., 28:451 (1990). Coat protein-mediated resistance has been conferred upon transformed plants against alfalfa mosaic virus, cucumber mosaic virus, tobacco streak virus, potato virus X, potato virus Y, tobacco etch virus, tobacco rattle virus, and tobacco mosaic virus. Id.

O. An insect-specific antibody or an immunotoxin derived therefrom. Thus, an antibody targeted to a critical metabolic function in the insect gut would inactivate an affected enzyme, killing the insect. Cf. Taylor, et al., Abstract #497, Seventh International Symposium on Molecular Plant-Microbe Interactions (Edinburgh, Scotland (1994)) (enzymatic inactivation in transgenic tobacco via production of single-chain antibody fragments).

P. A virus-specific antibody. See, for example, Tavladoraki, et al., Nature, 366:469 (1993), who show that transgenic plants expressing recombinant antibody genes are protected from virus attack.

Q. A developmental-arrestive protein produced in nature by a pathogen or a parasite. Thus, fungal endo-α-1,4-D-polygalacturonases facilitate fungal colonization and plant nutrient release by solubilizing plant cell wall homo-α-1,4-D-galacturonase. See, Lamb, et al., Bio/Technology, 10:1436 (1992). The cloning and characterization of a gene which encodes a bean endopolygalacturonase-inhibiting protein is described by Toubart, et al., Plant J., 2:367 (1992).

R. A developmental-arrestive protein produced in nature by a plant. For example, Logemann, et al., Bio/Technology, 10:305 (1992), have shown that transgenic plants expressing the barley ribosome-inactivating gene have an increased resistance to fungal disease.

S. Genes involved in the Systemic Acquired Resistance (SAR) Response and/or the pathogenesis-related genes. Briggs, S., Current Biology, 5(2) (1995); Pieterse & Van Loon, Curr. Opin. Plant Bio., 7(4):456-64 (2004) and Somssich, Cell, 113(7):815-6 (2003).

T. Antifungal genes. See, Cornelissen and Melchers, Plant Physiol., 101:709-712 (1993); Parijs, et al., Planta, 183:258-264 (1991) and Bushnell, et al., Can. J. of Plant Path., 20(2):137-149 (1998). See also, U.S. Pat. No. 6,875,907.

U. Detoxification genes, such as for fumonisin, beauvericin, moniliformin, and zearalenone, and their structurally related derivatives. For example, see U.S. Pat. No. 5,792,931.

V. Cystatin and cysteine proteinase inhibitors. See U.S. Pat. No. 7,205,453.

W. Defensin genes. See PCT Publication No. WO 03/000863 and U.S. Pat. No. 6,911,577.

2. Genes that Confer Resistance to an Herbicide, for Example:

A. An herbicide that inhibits the growing point or meristem, such as an imidazolinone or a sulfonylurea. Exemplary genes in this category code for mutant ALS and AHAS enzyme as described, for example, by Lee, et al., EMBO J., 7:1241 (1988) and Miki, et al., Theor. Appl. Genet., 80:449 (1990), respectively.

B. Glyphosate (resistance conferred by mutant 5-enolpyruvlshikimate-3-phosphate synthase (EPSP) and aroA genes, respectively) and other phosphono compounds such as glufosinate (phosphinothricin acetyl transferase (PAT) and Streptomyces hygroscopicus PAT, bar, genes), and pyridinoxy or phenoxy propionic acids and cyclohexones (ACCase inhibitor-encoding genes). See, for example, U.S. Pat. No. 4,940,835 to Shah, et al., which discloses the nucleotide sequence of a form of EPSP which can confer glyphosate resistance. A DNA molecule encoding a mutant aroA gene can be obtained under ATCC Accession No. 39256, and the nucleotide sequence of the mutant gene is disclosed in U.S. Pat. No. 4,769,061 to Comai. European Pat. Appl. No. 0 333 033 to Kumada, et al. and U.S. Pat. No. 4,975,374 to Goodman, et al., disclose nucleotide sequences of glutamine synthetase genes which confer resistance to herbicides such as L-phosphinothricin. The nucleotide sequence of a PAT gene is provided in European Pat. Appl. No. 0 242 246 to Leemans, et al. DeGreef, et al., Bio/Technology, 7:61 (1989), describe the production of transgenic plants that express chimeric bar genes coding for PAT activity. Exemplary of genes conferring resistance to phenoxy propionic acids and cyclohexones, such as sethoxydim and haloxyfop are the Acc1-S1, Acc1-S2, and Acc1-S3 genes described by Marshall, et al., Theor. Appl. Genet., 83:435 (1992).

C. An herbicide that inhibits photosynthesis, such as a triazine (psbA and gs+ genes) or a benzonitrile (nitrilase gene). Przibilla, et al., Plant Cell, 3:169 (1991), describe the transformation of Chlamydomonas with plasmids encoding mutant psbA genes. Nucleotide sequences for nitrilase genes are disclosed in U.S. Pat. No. 4,810,648 to Stalker, and DNA molecules containing these genes are available under ATCC Accession Nos. 53435, 67441, and 67442. Cloning and expression of DNA coding for a glutathione S-transferase is described by Hayes, et al., Biochem. J., 285:173 (1992).

3. Genes that Confer or Contribute to a Value-Added Trait, Such as:

A. Modified fatty acid metabolism, for example, by transforming a plant with an antisense gene of stearyl-ACP desaturase to increase stearic acid content of the plant. See, Knultzon, et al., Proc. Natl. Acad. Sci. U.S.A., 89:2624 (1992).

B. Decreased phytate content. 1) Introduction of a phytase-encoding gene would enhance breakdown of phytate, adding more free phosphate to the transformed plant. For example, see, Van Hartingsveldt, et al., Gene, 127:87 (1993), for a disclosure of the nucleotide sequence of an Aspergillus niger phytase gene; 2) A gene could be introduced that reduced phytate content. In maize, this, for example, could be accomplished by cloning and then reintroducing DNA associated with the single allele which is responsible for maize mutants characterized by low levels of phytic acid. See, Raboy, et al., Maydica, 35:383 (1990).

C. Modified carbohydrate composition effected, for example, by transforming plants with a gene coding for an enzyme that alters the branching pattern of starch. See, Shiroza, et al., J. Bacteol., 170:810 (1988) (nucleotide sequence of Streptococcus mutants fructosyltransferase gene); Steinmetz, et al., Mol. Gen. Genet., 20:220 (1985) (nucleotide sequence of Bacillus subtilis levansucrase gene); Pen, et al., Bio/Technology, 10:292 (1992) (production of transgenic plants that express Bacillus licheniformis α-amylase); Elliot, et al., Plant Molec. Biol., 21:515 (1993) (nucleotide sequences of tomato invertase genes); Sågaard, et al., J. Biol. Chem., 268:22480 (1993) (site-directed mutagenesis of barley α-amylase gene); and Fisher, et al., Plant Physiol., 102:1045 (1993) (maize endosperm starch branching enzyme II).

4. Genes that Control Male Sterility:

There are several available methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar, et al., and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. In addition to these methods, Albertsen, et al., U.S. Pat. No. 5,432,068, describes a system of nuclear male sterility which includes: identifying a gene which is critical to male fertility; silencing this native gene which is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not “on” resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning “on,” the promoter, which in turn allows the gene that confers male fertility to be transcribed.

A. A tapetum-specific gene, RTS, a rice anther-specific gene is required for male fertility and its promoter sequence directs tissue-specific gene expression in different plant species. Luo, Hong, et. al., Plant Molecular Biology., 62(3): 397-408(12) (2006). Introduction of a deacetylase gene under the control of a tapetum-specific promoter and with the application of the chemical N-Ac-PPT. See PCT Publication No. WO 01/29237.

B. Introduction of various stamen-specific promoters. Rice anther-specific promoters which are of particular utility in the production of transgenic male-sterile monocots and plants for restoring their fertility. See, U.S. Pat. No. 5,639,948. See also, PCT Publication Nos. WO 92/13956 and WO 92/13957.

C. Introduction of the barnase and the barstar genes. See, Paul, et al., Plant Mol. Biol., 19:611-622 (1992).

For additional examples of nuclear male and female sterility systems and genes, see also, U.S. Pat. Nos. 5,859,341, 6,297,426, 5,478,369, 5,824,524, 5,850,014, and 6,265,640. See also, Hanson, Maureen R., et. al., “Interactions of Mitochondrial and Nuclear Genes That Affect Male Gametophyte Development,” Plant Cell., 16:S154-S169 (2004), all of which are hereby incorporated by reference.

5. Genes that Create a Site for Site Specific DNA Integration:

This includes the introduction of FRT sites that may be used in the FLP/FRT system and/or Lox sites that may be used in the Cre/Loxp system. For example, see, Lyznik, et al., Site-Specific Recombination for Genetic Engineering in Plants, Plant Cell Rep, 21:925-932 (2003) and PCT Publication No. WO 99/25821, which are hereby incorporated by reference. Other systems that may be used include the Gin recombinase of phage Mu (Maeser, et al. (1991); Vicki Chandler, The Maize Handbook, ch. 118, Springer-Verlag (1994), the Pin recombinase of E. coli (Enomoto, et al. (1983)), and the R/RS system of the pSRi plasmid (Araki, et al. (1992)).

6. Genes that Affect Abiotic Stress Resistance:

Genes that affect abiotic stress resistance (including, but not limited to, flowering, panicle/glume and seed development, enhancement of nitrogen utilization efficiency, altered nitrogen responsiveness, drought resistance or tolerance, cold resistance or tolerance, and salt resistance or tolerance) and increased yield under stress. For example, see: Xiong, Lizhong, et al., “Disease Resistance and Abiotic Stress Tolerance in Rice Are Inversely Modulated by an Abscisic Acid-Inducible Mitogen-Activated Protein Kinase,” The Plant Cell., 15:745-759 (2003), where OsMAPK5 can positively regulate drought, salt, and cold tolerance and negatively modulate PR gene expression and broad-spectrum disease resistance in rice; Chen, Fang, et. al., “The Rice 14-3-3 Gene Family and its Involvement in Responses to Biotic and Abiotic Stress,” DNA Research, 13(2):53-63 (2006), where at least four rice GF14 genes, GF14b, GF14c, GF14e, and Gf14f, were differentially regulated by salinity, drought, wounding, and abscisic acid; PCT Publication No. WO 00/73475 where water use efficiency is altered through alteration of malate; U.S. Pat. Nos. 5,892,009, 5,965,705, 5,929,305, 5,891,859, 6,417,428, 6,664,446, 6,717,034, and 6,801,104, and PCT Publication Nos. WO 2000/060089, WO 2001/026459, WO 2001/035725, WO 2001/034726, WO 2001/035727, WO 2001/036444, WO 2001/036597, WO 2001/036598, WO 2002/015675, WO 2002/017430, WO 2002/077185, WO 2002/079403, WO 2003/013227, WO 2003/013228, WO 2003/014327, WO 2004/031349, WO 2004/076638, WO 98/09521, and WO 99/38977 describing genes, including CBF genes and transcription factors effective in mitigating the negative effects of freezing, high salinity, and drought on plants, as well as conferring other positive effects on plant phenotype; U.S. Publication No. 2004/0148654 and PCT Publication No. WO 01/36596 where abscisic acid is altered in plants resulting in improved plant phenotype such as increased yield and/or increased tolerance to abiotic stress; PCT Publication Nos. WO 2000/006341 and WO 04/090143, U.S. Publication No. 2004/0237147, and U.S. Pat. No. 6,992,237, where cytokinin expression is modified resulting in plants with increased stress tolerance, such as drought tolerance and/or increased yield. Also see, PCT Publication Nos. WO 02/02776, WO 2003/052063, WO 01/64898, JP 2002281975, and U.S. Pat. Nos. 6,084,153, 6,177,275, and 6,107,547 (enhancement of nitrogen utilization and altered nitrogen responsiveness). For ethylene alteration, see, U.S. Publication Nos. 2004/0128719 and 2003/0166197 and PCT Publication No. WO 2000/32761. For plant transcription factors or transcriptional regulators of abiotic stress, see, e.g., U.S. Publication Nos. 2004/0098764 and 2004/0078852.

Other genes and transcription factors that affect plant growth and agronomic traits such as yield, flowering, plant growth, and/or plant structure, can be introduced or introgressed into plants, see, e.g., PCT Publication Nos. WO 97/49811 (LHY), WO 98/56918 (ESD4), WO 97/10339, WO 96/14414 (CON), WO 96/38560, WO 01/21822 (VRN1), WO 00/44918 (VRN2), WO 99/49064 (GI), WO 00/46358 (FRI), WO 97/29123, WO 99/09174 (D8 and Rht), and U.S. Pat. Nos. 6,573,430 (TFL), 6,713,663 (FT), 6,794,560, 6,307,126 (GAI), and PCT Publication Nos. WO 2004/076638 and WO 2004/031349 (transcription factors).

Methods for Rice Transformation

Numerous methods for plant transformation have been developed, including biological and physical plant transformation protocols. See, for example, Miki, et al., “Procedures for Introducing Foreign DNA into Plants,” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 67-88 (1993)). In addition, expression vectors and in vitro culture methods for plant cell or tissue transformation and regeneration of plants are available. See, for example, Gruber, et al., “Vectors for Plant Transformation,” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 89-119 (1993).

A. Agrobacterium-mediated Transformation—One method for introducing an expression vector into plants is based on the natural transformation system of Agrobacterium. See, for example, Horsch, et al., Science, 227:1229 (1985). A. tumefaciens and A. rhizogenes are plant pathogenic soil bacteria which genetically transform plant cells. The Ti and Ri plasmids of A. tumefaciens and A. rhizogenes, respectively, carry genes responsible for genetic transformation of the plant. See, for example, Kado, C. I., Crit. Rev. Plant Sci., 10:1 (1991). Descriptions of Agrobacterium vector systems and methods for Agrobacterium-mediated gene transfer are provided by Gruber, et al., supra, Miki, et al., supra, and Moloney, et al., Plant Cell Reports, 8:238 (1989). See also, U.S. Pat. No. 5,591,616, issued Jan. 7, 1997.

B. Direct Gene Transfer—Despite the fact the host range for Agrobacterium-mediated transformation is broad, some major cereal crop species and gymnosperms have generally been recalcitrant to this mode of gene transfer, even though some success has recently been achieved in rice and corn. Hiei, et al., The Plant Journal, 6:271-282 (1994) and U.S. Pat. No. 5,591,616, issued Jan. 7, 1997. Several methods of plant transformation, collectively referred to as direct gene transfer, have been developed as an alternative to Agrobacterium-mediated transformation.

A generally applicable method of plant transformation is microprojectile-mediated transformation wherein DNA is carried on the surface of microprojectiles measuring 1 to 4 μm. The expression vector is introduced into plant tissues with a biolistic device that accelerates the microprojectiles to speeds of 300 to 600 m/s which is sufficient to penetrate plant cell walls and membranes. Sanford, et al., Part. Sci. Technol., 5:27 (1987); Sanford, J. C., Trends Biotech., 6:299 (1988); Klein, et al., Bio/Technology, 6:559-563 (1988); Sanford, J. C., Physiol Plant, 7:206 (1990); Klein, et al., Biotechnology, 10:268 (1992). In corn, several target tissues can be bombarded with DNA-coated microprojectiles in order to produce transgenic plants, including, for example, callus (Type I or Type II), immature embryos, and meristematic tissue.

Another method for physical delivery of DNA to plants is sonication of target cells. Zhang, et al., Bio/Technology, 9:996 (1991). Additionally, liposome and spheroplast fusion have been used to introduce expression vectors into plants. Deshayes, et al., EMBO J., 4:2731 (1985); Christou, et al., Proc Natl. Acad. Sci. U.S.A., 84:3962 (1987). Direct uptake of DNA into protoplasts using CaCl₂ precipitation, polyvinyl alcohol or poly-L-ornithine has also been reported. Hain, et al., Mol. Gen. Genet., 199:161 (1985) and Draper, et al., Plant Cell Physiol., 23:451 (1982). Electroporation of protoplasts and whole cells and tissues have also been described. Donn, et al., In Abstracts of VIIth International Congress on Plant Cell and Tissue Culture IAPTC, A2-38, p. 53 (1990); D'Halluin, et al., Plant Cell, 4:1495-1505 (1992); and Spencer, et al., Plant Mol. Biol., 24:51-61 (1994).

Following transformation of rice target tissues, expression of the above-described selectable marker genes allows for preferential selection of transformed cells, tissues, and/or plants using regeneration and selection methods now well known in the art.

Genetic Marker Profile Through SSR and First Generation Progeny

In addition to phenotypic observations, a plant can also be identified by its genotype. The genotype of a plant can be characterized through a genetic marker profile which can identify plants of the same variety or a related variety or be used to determine or validate a pedigree. Genetic marker profiles can be obtained by techniques such as Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs), which are also referred to as Microsatellites, and Single Nucleotide Polymorphisms (SNPs). For example, see, Cregan et. al, “An Integrated Genetic Linkage Map of the Soybean Genome,” Crop Science, 39:1464-1490 (1999), and Berry, et al., Assessing Probability of Ancestry Using Simple Sequence Repeat Profiles: Applications to Maize Inbred Lines and Soybean Varieties,” Genetics, 165:331-342 (2003), each of which are incorporated by reference herein in their entirety.

Particular markers used for these purposes are not limited to any particular set of markers, but are envisioned to include any type of marker and marker profile which provides a means of distinguishing varieties. One method of comparison is to use only homozygous loci for rice cultivar CL 181-AR.

Primers and PCR protocols for assaying these and other markers are widely known in the art. In addition to being used for identification of rice cultivar CL 181-AR and plant parts and plant cells of rice cultivar CL 181-AR, the genetic profile may be used to identify a rice plant produced through the use of rice cultivar CL 181-AR or to verify a pedigree for progeny plants produced through the use of rice cultivar CL 181-AR. The genetic marker profile is also useful in breeding and developing backcross conversions.

The present invention comprises a rice cultivar plant characterized by molecular and physiological data obtained from the representative sample of said cultivar deposited with the American Type Culture Collection (ATCC). Further provided by the invention is a rice hybrid plant formed by the combination of the disclosed rice plant or plant cell with another rice plant or cell.

Means of performing genetic marker profiles using SSR polymorphisms are well known in the art. SSRs are genetic markers based on polymorphisms in repeated nucleotide sequences, such as microsatellites. A marker system based on SSRs can be highly informative in linkage analysis relative to other marker systems in that multiple alleles may be present. Another advantage of this type of marker is that, through use of flanking primers, detection of SSRs can be achieved, for example, by the polymerase chain reaction (PCR), thereby eliminating the need for labor-intensive Southern hybridization. The PCR detection is done by use of two oligonucleotide primers flanking the polymorphic segment of repetitive DNA. Repeated cycles of heat denaturation of the DNA followed by annealing of the primers to their complementary sequences at low temperatures, and extension of the annealed primers with DNA polymerase, comprise the major part of the methodology.

Following amplification, markers can be scored by electrophoresis of the amplification products. Scoring of marker genotype is based on the size of the amplified fragment, which may be measured by the number of base pairs of the fragment. While variation in the primer used or in laboratory procedures can affect the reported fragment size, relative values should remain constant regardless of the specific primer or laboratory used. When comparing hybrids or varieties it is preferable if all SSR profiles are performed in the same lab.

Primers used are publicly available and may be found in for example in U.S. Pat. Nos. 7,232,940, 7,217,003, 7,250,556, 7,214,851, 7,195,887, and 7,192,774.

In addition, plants and plant parts substantially benefiting from the use of rice cultivar CL 181-AR in their development, such as rice cultivar CL 181-AR comprising a backcross conversion, transgene, or genetic sterility factor, may be identified by having a molecular marker profile with a high percent identity to rice cultivar CL 181-AR. Such a percent identity might be 95%, 96%, 97%, 98%, 99%, 99.5%, or 99.9% identical to rice cultivar CL 181-AR.

The SSR profile of rice cultivar CL 181-AR also can be used to identify essentially derived varieties and other progeny varieties developed using rice cultivar CL 181-AR, as well as cells and other plant parts thereof. Such plants may be developed using the markers identified in International Publication No. WO 00/31964, U.S. Pat. No. 6,162,967, and U.S. application Ser. No. 09/954,773. Progeny plants and plant parts produced using rice cultivar CL 181-AR may be identified by having a molecular marker profile of at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 99.5% genetic contribution from a rice hybrid or variety, as measured by either percent identity or percent similarity. Such progeny may be further characterized as being within a pedigree distance of rice cultivar CL 181-AR, such as within 1, 2, 3, 4, or 5 or fewer cross-pollinations to a rice plant other than rice cultivar CL 181-AR or a plant that has rice cultivar CL 181-AR as a progenitor. Unique molecular profiles may be identified with other molecular tools such as SNPs and RFLPs.

While determining the SSR genetic marker profile of the plants described supra, several unique SSR profiles may also be identified which did not appear in either parent of such rice plant. Such unique SSR profiles may arise during the breeding process from recombination or mutation. A combination of several unique alleles provides a means of identifying a plant variety, an F₁ progeny produced from such variety, and progeny produced from such rice plan.

The foregoing methods for transformation would typically be used for producing a transgenic cultivar. The transgenic cultivar could then be crossed, with another (non-transformed or transformed) cultivar, in order to produce a new transgenic cultivar. Alternatively, a genetic trait which has been engineered into a particular rice cultivar using the foregoing transformation techniques could be moved into another cultivar using traditional backcrossing techniques that are well known in the plant breeding arts. For example, a backcrossing approach could be used to move an engineered trait from a public, non-elite cultivar into an elite cultivar, or from a cultivar containing a foreign gene in its genome into a cultivar which does not contain that gene. As used herein, “crossing” can refer to a simple X by Y cross, or the process of backcrossing, depending on the context.

Gene Conversion

When the term “rice plant” is used in the context of the present invention, this also includes any gene conversions of that cultivar. The term gene converted plant as used herein refers to those rice plants which are developed by a plant breeding technique called backcrossing wherein essentially all of the desired morphological and physiological characteristics of a cultivar are recovered in addition to the one or more genes transferred into the cultivar via the backcrossing technique. Backcrossing methods can be used with the present invention to improve or introduce a characteristic into the cultivar. The term backcrossing as used herein refers to the repeated crossing of a hybrid progeny back to one of the parental rice plants, the recurrent parent, for that cultivar, i.e., backcrossing 1, 2, 3, 4, 5, 6, 7, 8, 9, or more times to the recurrent parent. The parental rice plant which contributes the gene for the desired characteristic is termed the nonrecurrent or donor parent. This terminology refers to the fact that the nonrecurrent parent is used one time in the backcross protocol and therefore does not recur. The parental rice plant to which the gene or genes from the nonrecurrent parent are transferred is known as the recurrent parent as it is used for several rounds in the backcrossing protocol (Poehlman & Sleper (1994); Fehr (1987)). In a typical backcross protocol, the original cultivar of interest (recurrent parent) is crossed to a second cultivar (nonrecurrent parent) that carries the single gene or genes of interest to be transferred. The resulting progeny from this cross are then crossed again to the recurrent parent and the process is repeated until a rice plant is obtained wherein essentially all of the desired morphological and physiological characteristics of the recurrent parent are recovered in the converted plant, in addition to one or more transferred genes from the nonrecurrent parent as determined at the 5% significance level when grown in the same environmental conditions.

The selection of a suitable recurrent parent is an important step for a successful backcrossing procedure. The goal of a backcross protocol is to alter or substitute a single trait or characteristic in the original cultivar. To accomplish this, one or more genes of the recurrent cultivar is modified or substituted with the desired gene or genes from the nonrecurrent parent, while retaining essentially all of the rest of the desired genetic, and therefore the desired physiological and morphological, constitution of the original cultivar. The choice of the particular nonrecurrent parent will depend on the purpose of the backcross; one of the major purposes is to add some commercially desirable, agronomically important trait to the plant. The exact backcrossing protocol will depend on the characteristic or trait being altered to determine an appropriate testing protocol. Although backcrossing methods are simplified when the characteristic being transferred is a dominant allele, a recessive allele may also be transferred. In this instance it may be necessary to introduce a test of the progeny to determine if the desired characteristic has been successfully transferred.

Many single gene traits have been identified that are not regularly selected for in the development of a new cultivar but that can be improved by backcrossing techniques. Single gene traits may or may not be transgenic. Examples of these traits include but are not limited to, male sterility, waxy starch, herbicide resistance, resistance for bacterial, fungal, or viral disease, insect resistance, male fertility, enhanced nutritional quality, industrial usage, yield stability and yield enhancement. These genes are generally inherited through the nucleus. Some known exceptions to this are the genes for male sterility, some of which are inherited cytoplasmically, but still act as single gene traits. Several of these single gene traits are described in U.S. Pat. Nos. 5,777,196, 5,948,957, and 5,969,212, the disclosures of which are specifically hereby incorporated by reference.

Introduction of a New Trait or Locus into Rice Cultivar CL 181-AR

Rice cultivar CL 181-AR represents a new base genetic hybrid into which a new locus or trait may be introgressed. Direct transformation and backcrossing represent two important methods that can be used to accomplish such an introgression. The term backcross conversion and single locus conversion are used interchangeably to designate the product of a backcrossing program.

Backcross Conversions of Rice Cultivar CL 181-AR

A backcross conversion of rice cultivar CL 181-AR occurs when DNA sequences are introduced through backcrossing (Hallauer, et al., “Corn Breeding,” Corn and Corn Improvements, No. 18, pp. 463-481 (1988)), with rice cultivar CL 181-AR utilized as the recurrent parent. Both naturally occurring and transgenic DNA sequences may be introduced through backcrossing techniques. A backcross conversion may produce a plant with a trait or locus conversion in at least two or more backcrosses, including at least 2 crosses, at least 3 crosses, at least 4 crosses, at least 5 crosses, and the like. Molecular marker assisted breeding or selection may be utilized to reduce the number of backcrosses necessary to achieve the backcross conversion. For example, see, Openshaw, S. J., et al., Marker-assisted Selection in Backcross Breeding, in: Proceedings Symposium of the Analysis of Molecular Data, Crop Science Society of America, Corvallis, Oreg. (August 1994), where it is demonstrated that a backcross conversion can be made in as few as two backcrosses.

The complexity of the backcross conversion method depends on the type of trait being transferred (single genes or closely linked genes as vs. unlinked genes), the level of expression of the trait, the type of inheritance (cytoplasmic or nuclear) and the types of parents included in the cross. It is understood by those of ordinary skill in the art that for single gene traits that are relatively easy to classify, the backcross method is effective and relatively easy to manage. (See, Hallauer, et al., in Corn and Corn Improvement, Sprague and Dudley, Third Ed. (1998)). Desired traits that may be transferred through backcross conversion include, but are not limited to, sterility (nuclear and cytoplasmic), fertility restoration, nutritional enhancements, drought tolerance, nitrogen utilization, altered fatty acid profile, low phytate, industrial enhancements, disease resistance (bacterial, fungal or viral), insect resistance, and herbicide resistance. In addition, an introgression site itself, such as an FRT site, Lox site, or other site specific integration site, may be inserted by backcrossing and utilized for direct insertion of one or more genes of interest into a specific plant variety. In some embodiments of the invention, the number of loci that may be backcrossed into rice cultivar CL 181-AR is at least 1, 2, 3, 4, or 5, and/or no more than 6, 5, 4, 3, or 2. A single locus may contain several transgenes, such as a transgene for disease resistance that, in the same expression vector, also contains a transgene for herbicide resistance. The gene for herbicide resistance may be used as a selectable marker and/or as a phenotypic trait. A single locus conversion of a site specific integration system allows for the integration of multiple genes at the converted loci.

Tissue Culture

Further reproduction of the variety can occur by tissue culture and regeneration. Tissue culture of various tissues of rice and regeneration of plants therefrom is well known and widely published. For example, reference may be had to Komatsuda, T., et al., Crop Sci., 31:333-337 (1991); Stephens, P. A., et al., Theor. Appl. Genet., 82:633-635 (1991); Komatsuda, T., et al., Plant Cell, Tissue and Organ Culture, 28:103-113 (1992); Dhir, S., et al., Plant Cell Reports, 11:285-289 (1992); Pandey, P., et al., Japan J. Breed., 42:1-5 (1992); and Shetty, K., et al., Plant Science, 81:245-251 (1992); as well as U.S. Pat. No. 5,024,944, issued Jun. 18, 1991 to Collins, et al., and U.S. Pat. No. 5,008,200, issued Apr. 16, 1991 to Ranch, et al. Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce rice plants having the physiological and morphological characteristics of rice variety CL 181-AR.

As used herein, the term “tissue culture” indicates a composition comprising isolated cells of the same or a different type or a collection of such cells organized into parts of a plant. Exemplary types of tissue cultures are protoplasts, calli, plant clumps, and plant cells that can generate tissue culture that are intact in plants or parts of plants, such as embryos, pollen, flowers, seeds, pods, leaves, stems, roots, root tips, anthers, and the like. Means for preparing and maintaining plant tissue culture are well known in the art. By way of example, a tissue culture comprising organs has been used to produce regenerated plants. U.S. Pat. Nos. 5,959,185; 5,973,234, and 5,977,445 describe certain techniques, the disclosures of which are incorporated herein by reference.

As used herein, the term “plant” includes plant cells, plant protoplasts, plant cells of tissue culture from which rice plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as pollen, flowers, embryos, ovules, seeds, pods, leaves, stems, pistils, anthers, and the like. Thus, another aspect of this invention is to provide for cells which upon growth and differentiation produce a cultivar having essentially all of the physiological and morphological characteristics of CL 181-AR.

The present invention contemplates a rice plant regenerated from a tissue culture of a variety (e.g., CL 181-AR) or hybrid plant of the present invention. As is well known in the art, tissue culture of rice can be used for the in vitro regeneration of a rice plant. Tissue culture of various tissues of rice and regeneration of plants therefrom is well known and widely published. For example, reference may be had to Chu, Q. R., et al., “Use of bridging parents with high anther culturability to improve plant regeneration and breeding value in rice,” Rice Biotechnology Quarterly, 38:25-26 (1999); Chu, Q. R., et al., “A novel plant regeneration medium for rice anther culture of Southern U.S. crosses,” Rice Biotechnology Quarterly, 35:15-16 (1998); Chu, Q. R., et al., “A novel basal medium for embryogenic callus induction of Southern US crosses,” Rice Biotechnology Quarterly, 32:19-20 (1997); and Oono, K., “Broadening the Genetic Variability By Tissue Culture Methods,” Jap. J. Breed., 33 (Suppl. 2), 306-307, illus. 1983. Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce rice plants having the physiological and morphological characteristics of variety CL 181-AR.

Duncan, et al., Planta, 165:322-332 (1985), reflects that 97% of the plants cultured that produced callus were capable of plant regeneration. Subsequent experiments with both cultivars and hybrids produced 91% regenerable callus that produced plants. In a further study in 1988, Songstad, et al., Plant Cell Reports, 7:262-265 (1988), reports several media additions that enhance regenerability of callus of two cultivars. Other published reports also indicated that “non-traditional” tissues are capable of producing somatic embryogenesis and plant regeneration. K. P. Rao, et al., Maize Genetics Cooperation Newsletter, 60:64-65 (1986), refers to somatic embryogenesis from glume callus cultures and B. V. Conger, et al., Plant Cell Reports, 6:345-347 (1987), indicates somatic embryogenesis from the tissue cultures of corn leaf segments. Thus, it is clear from the literature that the state of the art is such that these methods of obtaining plants are routinely used and have a very high rate of success.

Tissue culture of corn is described in European Patent Application Publication 160,390. Corn tissue culture procedures are also described in Green and Rhodes, “Plant Regeneration in Tissue Culture of Maize,” Maize for Biological Research, Plant Molecular Biology Association, Charlottesville, Va., 367-372 (1982), and in Duncan, et al., “The Production of Callus Capable of Plant Regeneration from Immature Embryos of Numerous Zea Mays Genotypes,” 165 Planta, 322:332 (1985). Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce corn plants having the physiological and morphological characteristics of rice cultivar CL 181-AR.

The utility of rice cultivar CL 181-AR also extends to crosses with other species. Commonly, suitable species will be of the family Graminaceae, and especially of the genera Zea, Tripsacum, Croix, Schlerachne, Polytoca, Chionachne, and Trilobachne, of the tribe Maydeae.

This invention also is directed to methods for producing a rice plant by crossing a first parent rice plant with a second parent rice plant wherein the first or second parent rice plant is a rice plant of the variety CL 181-AR. Further, both first and second parent rice plants can come from the rice variety CL 181-AR. Thus, any such methods using the rice variety CL 181-AR are part of this invention: selling, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using rice variety CL 181-AR as a parent are within the scope of this invention, including those developed from varieties derived from rice variety CL 181-AR. Advantageously, the rice variety could be used in crosses with other, different, rice plants to produce the first generation (F₁) rice hybrid seeds and plants with superior characteristics. The variety of the invention can also be used for transformation where exogenous genes are introduced and expressed by the variety of the invention. Genetic variants created either through traditional breeding methods using variety CL 181-AR or through transformation of CL 181-AR by any of a number of protocols known to those of skill in the art are intended to be within the scope of this invention.

The following describes breeding methods that may be used with cultivar CL 181-AR in the development of further rice plants. One such embodiment is a method for developing a CL 181-AR progeny rice plant in a rice plant breeding program comprising: obtaining the rice plant, or a part thereof, of cultivar CL 181-AR utilizing said plant or plant part as a source of breeding material and selecting a CL 181-AR progeny plant with molecular markers in common with CL 181-AR and/or with morphological and/or physiological characteristics selected from the characteristics listed in Tables 2 or 3. Breeding steps that may be used in the rice plant breeding program include pedigree breeding, back crossing, mutation breeding, and recurrent selection. In conjunction with these steps, techniques such as RFLP-enhanced selection, genetic marker enhanced selection (for example SSR markers) and the making of double haploids may be utilized.

Another method involves producing a population of cultivar CL 181-AR progeny rice plants, comprising crossing cultivar CL 181-AR with another rice plant, thereby producing a population of rice plants, which, on average, derive 50% of their alleles from cultivar CL 181-AR. A plant of this population may be selected and repeatedly selfed or sibbed with a rice cultivar resulting from these successive filial generations. One embodiment of this invention is the rice cultivar produced by this method and that has obtained at least 50% of its alleles from cultivar CL 181-AR.

One of ordinary skill in the art of plant breeding would know how to evaluate the traits of two plant varieties to determine if there is no significant difference between the two traits expressed by those varieties. For example, see, Fehr and Walt, Principles of Cultivar Development, pp. 261-286 (1987). Thus the invention includes rice cultivar CL 181-AR progeny rice plants comprising a combination of at least two CL 181-AR traits selected from the group consisting of those listed in the Tables herein, or the CL 181-AR combination of traits listed in the Summary of the Invention, so that said progeny rice plant is not significantly different for said traits than rice cultivar CL 181-AR as determined at the 5% significance level when grown in the same environment. Using techniques described herein, molecular markers may be used to identify said progeny plant as a CL 181-AR progeny plant. Mean trait values may be used to determine whether trait differences are significant, and preferably the traits are measured on plants grown under the same environmental conditions. Once such a variety is developed its value is substantial since it is important to advance the germplasm base as a whole in order to maintain or improve traits such as yield, disease resistance, pest resistance, and plant performance in extreme environmental conditions.

Progeny of rice cultivar CL 181-AR may also be characterized through their filial relationship with rice cultivar CL 181-AR, as for example, being within a certain number of breeding crosses of rice cultivar CL 181-AR. A breeding cross is a cross made to introduce new genetics into the progeny, and is distinguished from a cross, such as a self or a sib cross, made to select among existing genetic alleles. The lower the number of breeding crosses in the pedigree, the closer the relationship between rice cultivar CL 181-AR and its progeny. For example, progeny produced by the methods described herein may be within 1, 2, 3, 4, or 5 breeding crosses of rice cultivar CL 181-AR.

Pedigree Breeding

Pedigree breeding starts with the crossing of two genotypes, such as rice cultivar CL 181-AR and another rice plant having one or more desirable characteristics that is lacking or which complements rice cultivar CL 181-AR. If the two original parents do not provide all the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive filial generations. In the succeeding filial generations the heterozygous condition gives way to homogeneous varieties as a result of self-pollination and selection. Typically in the pedigree method of breeding, five or more successive filial generations of selfing and selection is practiced: F₁ to F₂; F₂ to F₃; F₃ to F₄; F₄ to F₅; etc. After a sufficient amount of inbreeding, successive filial generations will serve to increase seed of the developed variety. Preferably, the developed variety comprises homozygous alleles at about 95% or more of its loci.

In addition to being used to create a backcross conversion, backcrossing can also be used in combination with pedigree breeding. As discussed previously, backcrossing can be used to transfer one or more specifically desirable traits from one variety, the donor parent, to a developed variety called the recurrent parent, which has overall good agronomic characteristics yet lacks that desirable trait or traits. However, the same procedure can be used to move the progeny toward the genotype of the recurrent parent but at the same time retain many components of the nonrecurrent parent by stopping the backcrossing at an early stage and proceeding with selfing and selection. For example, a rice variety may be crossed with another rice variety to produce a first generation progeny plant. The first generation progeny plant may then be backcrossed to one of its parent varieties to create a BC₁ or BC₂. Progeny are selfed and selected so that the newly developed variety has many of the attributes of the recurrent parent and yet several of the desired attributes of the nonrecurrent parent. This approach leverages the value and strengths of the recurrent parent for use in new rice varieties.

Therefore, an embodiment of this invention is a method of making a backcross conversion of rice cultivar CL 181-AR, comprising the steps of crossing a plant of rice cultivar CL 181-AR with a donor plant comprising a desired trait, selecting an F₁ progeny plant comprising the desired trait, and backcrossing the selected F₁ progeny plant to a plant of rice cultivar CL 181-AR. This method may further comprise the step of obtaining a molecular marker profile of rice cultivar CL 181-AR and using the molecular marker profile to select for a progeny plant with the desired trait and the molecular marker profile of rice cultivar CL 181-AR. In one embodiment the desired trait is a mutant gene or transgene present in the donor parent.

Recurrent Selection and Mass Selection

Recurrent selection is a method used in a plant breeding program to improve a population of plants. Rice cultivar CL 181-AR is suitable for use in a recurrent selection program. The method entails individual plants cross pollinating with each other to form progeny. The progeny are grown and the superior progeny selected by any number of selection methods, which include individual plant, half-sib progeny, full-sib progeny and selfed progeny. The selected progeny are cross pollinated with each other to form progeny for another population. This population is planted and again superior plants are selected to cross pollinate with each other. Recurrent selection is a cyclical process and therefore can be repeated as many times as desired. The objective of recurrent selection is to improve the traits of a population. The improved population can then be used as a source of breeding material to obtain new varieties for commercial or breeding use, including the production of a synthetic cultivar. A synthetic cultivar is the resultant progeny formed by the inter-crossing of several selected varieties.

Mass selection is a useful technique when used in conjunction with molecular marker enhanced selection. In mass selection seeds from individuals are selected based on phenotype or genotype. These selected seeds are then bulked and used to grow the next generation. Bulk selection requires growing a population of plants in a bulk plot, allowing the plants to self-pollinate, harvesting the seed in bulk and then using a sample of the seed harvested in bulk to plant the next generation. Also, instead of self pollination, directed pollination could be used as part of the breeding program.

Mutation Breeding

Mutation breeding is another method of introducing new traits into rice cultivar CL 181-AR. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation; such as X-rays, Gamma rays (e.g., cobalt 60 or cesium 137), neutrons (product of nuclear fission by uranium 235 in an atomic reactor), Beta radiation (emitted from radioisotopes such as phosphorus 32 or carbon 14), or ultraviolet radiation (preferably from 2500 to 2900 nm), or chemical mutagens (such as base analogues (5-bromo-uracil), related compounds (8-ethoxy caffeine), antibiotics (streptonigrin), alkylating agents (sulfur mustards, nitrogen mustards, epoxides, ethylenamines, sulfates, sulfonates, sulfones, lactones), azide, hydroxylamine, nitrous acid, or acridines. Once a desired trait is observed through mutagenesis the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in “Principles of Cultivar Development,” Fehr, Macmillan Publishing Company (1983). In addition, mutations created in other rice plants may be used to produce a backcross conversion of rice cultivar CL 181-AR that comprises such mutation.

Breeding with Molecular Markers

Molecular markers may be used in plant breeding methods utilizing rice cultivar CL 181-AR.

Isozyme Electrophoresis and RFLPs have been widely used to determine genetic composition. See, for example, Dinka, S. J., et al., “Predicting the size of the progeny mapping population required to positionally clone a gene,” Genetics., 176(4):2035-54 (2007); Gonzalez, C., et al., “Molecular and pathogenic characterization of new Xanthomonas oryzae strains from West Africa,” Mol. Plant Microbe Interact., 20(5):534-546 (2007); Jin, H., et al., “Molecular and cytogenic characterization of an Oryza officinalis-O. sativa chromosome 4 addition line and its progenies,” Plant Mol. Biol., 62(4-5):769-777 (2006); Pan, G., et al., “Map-based cloning of a novel rice cytochrome P450 gene CYP81A6 that confers resistance to two different classes of herbicides,” Plant Mol. Biol., 61(6):933-943 (2006); Huang, W., et al., “RFLP analysis for mitochondrial genome of CMS-rice,” Journal of Genetics and Genomics., 33(4):330-338 (2007); Yan, C. J., et al., “Identification and characterization of a major QTL responsible for erect panicle trait in japonica rice (Oryza sativa L.),” Theor. Appl. Genetics., DOI:10.1007/s00122-007-0635-9 (2007); and I. K. Vasil (ed.), DNA-based markers in plants, Kluwer Academic Press Dordrecht, the Netherlands.

SSR technology is currently the most efficient and practical marker technology; more marker loci can be routinely used and more alleles per marker locus can be found using SSRs in comparison to RFLPs. Gealy, David, et al., “Insights into the Parentage of Rice/red Rice Crosses Using SSR Analysis of US Rice Cultivars and Red Rice Populations,” Rice Technical Working Group Meeting Proceedings, Abstract, p. 179; Lawson, Mark J., et al., “Distinct Patterns of SSR Distribution in the Arabidopsis thaliana and rice genomes,” Genome Biology., 7:R14 (2006); Nagaraju, J., et al., “Genetic Analysis of Traditional and Evolved Basmati and Non-Basmati Rice Varieties by Using Fluorescence-based ISSR-PCR and SSR Markers,” Proc. Nat. Acad. Sci. USA., 99(9):5836-5841 (2002); and Lu, Hong, et al., “Population Structure and Breeding Patterns of 145 US Rice Cultivars Based on SSR Marker Analysis,” Crop Science, 45:66-76 (2005). Single Nucleotide Polymorphisms may also be used to identify the unique genetic composition of the invention and progeny varieties retaining that unique genetic composition. Various molecular marker techniques may be used in combination to enhance overall resolution.

Rice DNA molecular marker linkage maps have been rapidly constructed and widely implemented in genetic studies such as in Zhu, J. H., et al., “Toward rice genome scanning by map-based AFLP fingerprinting,” Mol. Gene Genetics., 261(1):184-195 (1999); Cheng, Z., et al., “Toward a cytological characterization of the rice genome,” Genome Research., 11(12):2133-2141 (2001); Ahn, S., et al., “Comparative linkage maps of the rice and maize genomes,” Proc. Natl. Acad. Sci. USA, 90(17):7980-7984 (1993); and Kao, F. I., et al., “An integrated map of Oryza sativa L. chromosome 5,” Theor. Appl. Genet., 112(5):891-902 (2006). Sequences and PCR conditions of SSR Loci in rice as well as the most current genetic map may be found in RiceBLAST and the TIGR Rice Genome Annotation on the World Wide Web.

One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers, which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome.

Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select for the genome of the recurrent parent and against the genome of the donor parent. Using this procedure can minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program. The use of molecular markers in the selection process is often called genetic marker enhanced selection. Molecular markers may also be used to identify and exclude certain sources of germplasm as parental varieties or ancestors of a plant by providing a means of tracking genetic profiles through crosses.

Production of Double Haploids

The production of double haploids can also be used for the development of plants with a homozygous phenotype in the breeding program. For example, a rice plant for which rice cultivar CL 181-AR is a parent can be used to produce double haploid plants. Double haploids are produced by the doubling of a set of chromosomes (1N) from a heterozygous plant to produce a completely homozygous individual. For example, see, Wan, et al., “Efficient Production of Doubled Haploid Plants Through Colchicine Treatment of Anther-Derived Maize Callus,” Theoretical and Applied Genetics, 77:889-892 (1989), and U.S. Pat. No. 7,135,615.

Methods for obtaining haploid plants are also disclosed in Kobayashi, M., et al., Journ. of Heredity, 71(1):9-14 (1980), Pollacsek, M., 12(3):247-251, Agronomie, Paris (1992); Cho-Un-Haing, et al., Journ. of Plant Biol., 39(3):185-188 (1996); Verdoodt, L., et al., 96(2):294-300 (February 1998); Genetic Manipulation in Plant Breeding, Proceedings International Symposium Organized by EUCARPIA, Berlin, Germany (Sep. 8-13, 1985); Thomas, W J K, et al., “Doubled haploids in breeding,” in Doubled Haploid Production in Crop Plants, Maluszynski, M., et al. (Eds.), Dordrecht, The Netherland Kluwer Academic Publishers, pp. 337-349 (2003).

Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Allard (1960); Simmonds (1979); Sneep, et al. (1979); Fehr (1987)).

The seed of rice cultivar CL 181-AR, the plant produced from the cultivar seed, the hybrid rice plant produced from the crossing of the cultivar, hybrid seed, and various parts of the hybrid rice plant and transgenic versions of the foregoing, can be utilized for human food, livestock feed, and as a raw material in industry.

The present invention provides methods for producing an herbicide-resistant rice plant through conventional plant breeding involving sexual reproduction. The methods comprise crossing a first rice plant that is a plant of rice cultivar CL 181-AR to a second rice plant that is not resistant to an herbicide. The methods of the invention can further involve one or more generations of backcrossing the progeny rice plants of the first cross to a rice plant of the same line or genotype as either the first or second rice plant. Alternatively, the progeny of the first cross or any subsequent cross can be crossed to a third rice plant that is of a different line or genotype than either the first or second rice plant. The methods of the invention can additionally involve selecting rice plants that comprise the herbicide tolerance characteristics of the first rice plant.

The present invention further provides methods for increasing the herbicide-resistance of a rice plant, particularly an herbicide-resistant rice plant, through conventional plant breeding involving sexual reproduction. The methods comprise crossing a first rice plant that is a plant of rice cultivar CL 181-AR to a second rice plant that may or may not be resistant to the same herbicides as the plant of rice cultivar CL 181-AR or may be resistant to different herbicide or herbicides than the first rice plant. The progeny rice plants produced by this method of the present invention have increased resistance to an herbicide when compared to either the first or second rice plant or both. When the first and second rice plants are resistant to different herbicides, the progeny plants will have the combined herbicide tolerance characteristics of the first and second rice plants. The methods of the invention can further involve one or more generations of backcrossing the progeny rice plants of the first cross to a rice plant of the same line or genotype as either the first or second rice plant. Alternatively, the progeny of the first cross or any subsequent cross can be crossed to a third plant that is of a different line or genotype than either the first or second plant. The methods of the invention can additionally involve selecting rice plants that comprise the herbicide tolerance characteristics of the first rice plant, the second rice plant, or both the first and the second rice plants.

TABLES

In Table 2, agronomic characteristics are shown for rice cultivar CL 181-AR and for six other rice cultivars. These data are the result of the Arkansas Rice Performance Trials (ARPT) conducted in 2007. (Stuttgart, Rice Research and Extension Center (RREC); Keiser, Northeast Research and Extension Center (NEREC); Rohwer, Southeast Research and Extension Center (SEREC-RD); Clay Co. and Jackson Co.). Column one shows the variety, column two shows the yield in bushels per acre, column three shows the plant height in inches, column four shows the maturity in days at 50% heading, column five shows the kernel weight in milligrams and column six shows the milling percent head rice (or whole kernel rice) as compared to the percent of total milled rice.

TABLE 2 Kernel Yield Height Maturity weight Milling Variety (BU/AC) (IN.) (50% HD) (mg) HR:TOT CL 181-AR 162 32 89 18.1 55:69 CL 142-AR 191 44 89 19.7 46:70 CL171-AR 167 39 90 16.7 57:71 CL161 155 38 89 16.7 61:70 Francis 185 38 87 17.2 53:70 Wells 185 41 88 18.7 48:70 Cocodrie 163 36 88 17.9 61:70 C.V.₀₅ 10.3

In Table 3, agronomic characteristics are shown for rice cultivar CL 181-AR and for seven other rice cultivars. These data are the result of the Arkansas Rice Performance Trials (ARPT) conducted in 2008 (Stuttgart, RREC; Keiser, NEREC; Rohwer, SEREC-RD; Clay Co. and Jackson Co.). Column one shows the variety, column two shows the yield in bushels per acre, column three shows the plant height in inches, column four shows the maturity in days at 50% heading, column five shows the kernel weight in milligrams and column six shows the milling percent head rice (or whole kernel rice) as compared to the percent of total milled rice.

TABLE 3 Kernel Yield Height Maturity weight Milling Variety (BU/AC) (IN.) (50% HD) (mg) HR:TOT CL 181-AR 152 35 92 18.8 59:71 CL 142-AR 155 44 90 20.0 55:71 CL171-AR 136 39 91 17.4 57:72 CL161 142 38 91 16.1 60:71 CL131 138 33 87 17.5 63:73 Francis 170 39 90 17.4 62:72 Wells 165 40 92 19.0 56:72 Cocodrie 148 36 88 17.7 63:72 C.V.₀₅ 12.1

In Table 4, agronomic characteristics are shown for rice cultivar CL 181-AR and five other rice cultivars. These data are the result of trials at the Arkansas Rice Performance Trials (ARPT) from 2007 to 2008. Column one shows the variety; column two gives the yield for each variety in bushels per acre; column three shows the height in inches for the varieties; column four shows the maturity at 50% heading in days; column five gives the milled kernel weight in milligrams, and column six gives the milling percent head rice (or whole kernel rice) as compared to the percent of total milled rice.

TABLE 4 Kernel Yield Height Maturity weight Milling Variety (BU/AC) (IN.) (50% HD) (mg) HR:TOT CL 181-AR 157 34 91 18.5 57:70 CL 142-AR 173 44 90 19.9 50:71 CL171-AR 151 39 91 17.1 57:72 CL161 149 38 90 16.4 60:71 Francis 177 39 89 17.3 57:71 Wells 175 41 90 18.9 51:71 Cocodrie 156 36 88 17.8 62:71

In Table 5, agronomic characteristics are shown for rice cultivar CL 181-AR and six other rice cultivars. The data are the result of trials at the Arkansas Rice Performance Trials (ARPT) from 2007. Column one shows the variety, columns two to six give the average grain yield for each of 5 different locations for each variety in bushels per acre, column eight gives the average grain yield for the 5 locations, columns eight to eleven show the average head rice (%) to total rice (%) ratio for each of 4 different locations and column twelve shows the average head rice (%) to total rice (%) ratio for the 4 locations.

TABLE 5 Grain Yield (BU/AC)^(a) Head Rice(%):Total Rice(%)^(b) Variety RREC NEREC SEREC-RD CC JC AVE RREC NEREC CC JC AVE CL 181-AR 142 183 82 187 218 162 60:70 50:67 57:70 55:71 55:69 CL 142-AR 171 182 150 204 251 191 50:72 35:69 58:71 43:71 46:70 CL171-AR 142 180 105 197 210 167 63:72 56:69 56:72 56:72 57:71 CL161 140 122 113 189 212 155 66:72 52:67 64:71 64:71 61:70 Francis 199 93 163 218 249 185 62:72 43:68 57:71 55:71 53:70 Wells 172 168 150 203 230 185 54:72 33:66 52:72 53:72 48:70 Cocodrie 176 144 95 162 238 163 62:72 58:69 62:70 63:71 61:70 C.V._(.05) 5.3 16.2 13.6 8.4 7.8 10.3 ^(a)2007 consisted of five locations: Rice Research and Extension Center (RREC), Stuttgart, AR; Northeast Research and Extension Center (NEREC), Keiser, AR; Southeast Research and Extension Center Rohwer Division (SEREC-RD), Rohwer, AR; Clay County producer field (CC); and Jackson County producer field (JC). ^(b)Milling figures are head rice:total milled rice.

In Table 6, agronomic characteristics are shown for the present invention, CL 181-AR and seven other rice cultivars. The data are the result of trials at the Arkansas Rice Performance Trials (ARPT) from 2008. Column one shows the variety, columns two to six give the average grain yield for each of 5 different locations for each variety in bushels per acre, column seven shows the average grain yield for the 5 locations, columns eight to ten show the average head rice (%) to total rice (%) ratio for each of 3 different locations and column eleven shows the average head rice (%) to total rice (%) ratio for the 3 locations.

TABLE 6 Grain Yield (BU/AC)^(a) Head Rice(%):Total Rice(%)^(b) Variety RREC PTES NEREC SEREC-RD JC AVE RREC NEREC JC AVE CL 181-AR 152 152 184 118 153 152 65:70 52:69 64:74 59:71 CL 142-AR 171 134 184 149 135 155 62:70 55:71 49:72 55:71 CL171-AR 160 121 162 105 130 136 64:72 60:72 50:71 57:72 CL161 176 117 146 119 153 142 66:71 64:73 51:70 60:71 CL131 138 130 172 131 121 138 67:72 65:72 59:75 63:73 Francis 196 167 187 138 163 170 63:70 59:71 64:74 62:72 Wells 194 177 172 151 133 165 66:74 60:72 45:71 56:72 Cocodrie 158 150 173 117 144 148 66:71 67:74 58:72 63:72 C.V._(.05) 5.4 7.7 13.6 11.9 12.6 12.1 ^(a)2008 consisted of five locations: Rice Research and Extension Center (RREC), Stuttgart; Pine Tree Experiment Station (PTES), Colt, AR; Northeast Research and Extension Center (NEREC), Keiser, AR; Southeast Research and Extension Center Rohwer Division (SEREC-RD), Rohwer, AR; and Jackson County producer field (JC). ^(b)Milling figures are head rice:total milled rice.

In Table 7, agronomic characteristics are shown for rice cultivar CL 181-AR, and six other rice cultivars. The data are the result of an average of the trials at the Arkansas Rice Performance Trials (ARPT) from 2007 to 2008. Column one shows the variety, columns two to seven give the average grain yield for each of 6 different locations for each variety in bushels per acre, column eight shows the average grain yield for the 6 locations, columns nine to twelve show the average head rice (%) to total rice (%) ratio for each of 4 different locations and column thirteen shows the average head rice (%) to total rice (%) ratio for the 4 locations.

TABLE 7 Grain Yield (BU/AC)^(a) Head Rice(%):Total Rice(%)^(b) Variety RREC PTES NEREC SEREC-RD CC JC AVE RREC NEREC CC JC AVE CL 181-AR 147 152 184 100 187 186 157 63:70 51:68 57:70 60:73 57:70 CL 142-AR 171 134 183 150 204 193 173 56:71 45:70 58:71 46:72 50:71 CL171-AR 151 121 171 105 197 170 151 64:72 58:71 56:72 53:72 57:72 CL161 158 117 134 116 189 183 149 66:72 58:70 64:71 57:71 60:71 Francis 197 167 140 151 218 206 177 63:71 51:69 57:71 60:73 57:71 Wells 183 177 170 151 203 182 175 60:73 46:69 52:72 49:72 51:71 Cocodrie 167 150 159 106 162 191 156 64:72 62:71 62:70 61:72 62:71 ^(a)2007 consisted of six locations: Rice Research and Extension Center (RREC), Stuttgart, AR; Northeast Research and Extension Center (NEREC), Keiser, AR; Southeast Research and Extension Center Rohwer Division (SEREC-RD), Rohwer, AR; Clay County producer field (CC); and Jackson County producer field (JC); and 2008 RREC, Pine Tree Experiment Station (PTES), Colt, AR; NEREC, SEREC-RD, and JC. ^(b)Milling figures are head rice:total milled rice.

In Table 8, agronomic characteristics are shown for rice cultivar CL 181-AR and 5 other rice cultivars. The data are results of trials from the Clearfield Arkansas Rice Performance Trials (ARPT) conducted in 2007. Column one shows the variety, columns two to three show the grain yield in bushels per acre for 2 locations, column four shows the average grain yield for the 2 locations, column five shows the height in inches, column six shows the maturity in number of days from emergence to 50% heading, columns seven to eight show the percent lodging for 2 locations, column nine shows the average % lodging for the 2 locations, columns ten to eleven show the head rice (%) to total rice (%) ratio for 2 locations and column twelve shows the average head rice (%) to total rice (%) ratio for the 2 locations.

TABLE 8 Grain Yield (BU/AC)^(a) HGT^(c) MAT.^(d) % Lodging^(e) Milling (HR:TOT)^(f) Variety RREC^(b) NEREC AVE (IN.) (50% HD) RREC NEREC AVE RREC NEREC AVE CL 181-AR 155 210 182 37 87 0 10 5 57:70 60:70 59:70 CL 142-AR 122 165 143 47 88 25 63 44 42:73 42:70 42:71 CL171-AR 130 177 153 41 90 25 33 29 60:72 57:71 58:72 CL161 99 101 100 40 89 67 57 62 62:70 60:70 61:70 CLXL729 124 87 105 42 86 67 43 55 52:70 45:68 49:69 CLXL730 93 85 89 44 86 44 78 80 52:72 46:69 49:70 ^(a)Rice Research and Extension Center (RREC), Stuttgart, AR and Northeast Research and Extension Center (NEREC), Keiser, AR. ^(b)RREC was planted mid May and rain and wind caused delayed harvest and lodging; shattering was a problem for hybrids. ^(c)HGT is height in inches. ^(d)MAT is maturity number of days from emergence to 50% heading. ^(e)NEREC was planted on April 30 and could not be harvested on time due to rains and a storm caused tremendous lodging. Shattering was a problem for the hybrid lines. ^(f)Milling figures are head rice:total milled rice ratio.

In Table 9, agronomic characteristics are shown for rice cultivar CL 181-AR and 5 other rice cultivars. The data are results of trials from the Clearfield Arkansas Rice Performance Trials (ARPT) conducted in 2008. Column one shows the variety, columns two to three show the grain yield in bushels per acre for 2 locations, column four shows the average grain yield for the 2 locations, column five shows the height in inches, column six shows the maturity in number of days from emergence to 50% heading, columns seven to eight show the percent lodging for 2 locations, column nine shows the average % lodging for the 2 locations, columns ten to eleven show the head rice (%) to total rice (%) ratio for 2 locations and column twelve shows the average head rice (%) to total rice (%) ratio for the 2 locations.

TABLE 9 Grain Yield (BU/AC)^(a) HGT^(c) MAT.^(d) % Lodging Milling (HR:TOT)^(e) Variety RREC LK^(b) AVE (IN.) (50% HD) RREC PC AVE RREC LK AVE CL 181-AR 190 113 152 34 95 0 0 0 69:72 64:74 67:73 CL 142-AR 178 103 140 40 94 27 0 13 68:74 62:76 65:75 CL171-AR 155 99 127 38 96 0 0 0 67:72 67:76 67:74 CL161 177 106 142 39 95 17 0 8 70:73 68:77 69:75 CL131 170 111 141 34 92 3 0 2 70:75 71:77 70:76 CL151 195 109 152 36 93 60 0 30 68:73 59:74 63:73 ^(a)Rice Research and Extension Center (RREC), Stuttgart, AR and University of Arkansas Pine Bluff Farm (LK), Lonoke, AR. ^(b)LK was planted late on Jun. 5, 2008. ^(c)HGT is height in inches. ^(d)MAT is maturity number of days from emergence to 50% heading. ^(e)Milling figures are head rice:total milled rice ratio.

In Table 10, agronomic characteristics are shown for rice cultivar CL 181-AR and 3 other rice cultivars. The data are averages of results from the Clearfield Arkansas Rice Performance Trials (ARPT) conducted from 2007 to 2008. Column one shows the variety, columns two to four show the grain yield in bushels per acre for 3 locations, column five shows the average grain yield for the 3 locations, column six shows the height in inches, column seven shows the maturity in number of days from emergence to 50% heading, columns eight to ten show the head rice (%) to total rice (%) ratio for 3 locations and column eleven shows the average head rice (%) to total rice (%) ratio for the 3 locations.

TABLE 10 Grain Yield (BU/AC)^(a) HGT^(b) MAT.^(c) Milling (HR:TOT)^(d) Variety RREC NEREC LK AVE (IN.) (50% HD) RREC NEREC LK AVE CL 181-AR 173 210 113 167 36 91 63:71 60:70 64:74 63:72 CL 142-AR 150 165 103 142 44 91 55:74 42:70 62:76 54:78 CL171-AR 143 177 99 140 40 93 64:72 57:71 67:76 63:73 CL161 138 101 106 121 40 92 66:72 60:70 68:77 65:73 ^(a)Rice Research and Extension Center (RREC), Stuttgart, AR (2007-2008); Northeast Research and Extension Center (NEREC), Keiser, AR (2007); and University of Arkansas Pine Bluff Farm (LK), Lonoke, AR (2008). ^(b)HGT is height in inches. ^(c)MAT is maturity number of days from emergence to 50% heading. ^(d)Milling figures are head rice:total milled rice ratio.

In Table 11, kernel characteristics are shown for rice cultivars CL 181-AR and CL 181-AR. The data are averages of the following trials, 2005 IMI SIT RREC, 2006 IMI SIT, RREC, 2007 ARPT and IMI ARPT, RREC, 2008 ARPT and IMI ARPT and 2008 Breeder Head Row Seed RREC. Column 1 shows the variety, column 2 shows the class, column 3 shows the length in millimeters, column 4 shows the width in millimeters, column 5 shows the thickness in millimeters, column 6 shows the length to width ratio and column 7 shows the kernel weight in milligrams. The numbers in the tables are averages for the tests listed. Rice cultivar CL 142-AR had a range of 25.5 to 29.5 mg/kernel in these tests and CL 181-AR had a range of 22.0 to 26.5 mg/kernel for the same tests.

TABLE 11 Variety Class Length Width Thickness L/W Kernel CL142-AR Rough 9.08 2.64 2.01 3.44 26.9 CL181-AR Rough 8.96 2.47 1.97 3.63 24.2 CL142-AR Brown 7.28 2.38 1.76 3.06 23.3 CL181-AR Brown 7.08 2.29 1.73 3.09 19.6 CL142-AR Milled 6.80 2.24 1.70 3.04 20.4 CL181-AR Milled 6.68 2.14 1.67 3.12 17.9 Disease Evaluations for Rice Cultivar CL 181-AR Greenhouse Blast Tests

Rice diseases are usually rated visually on a 0-9 scale to estimate degree of severity. Numerical data is often converted to this scale. A rating of zero indicates complete disease immunity. A rating of one to three indicates resistance where little loss occurs and in the case of rice blast pathogen growth is restricted considerably. Conversely, a nine rating indicates maximum disease susceptibility, which typically results in complete plant death and/or yield loss. Depending upon the disease in question, a disease rating of four to six is usually indicative of acceptable disease resistance under conditions slightly favoring the pathogen. Numerical ratings are sometimes converted to letter symbols where 0-3=R (resistant), 3-4=MR (moderately resistant), 5-6=MS (moderately susceptible) 7=S (susceptible) and 8-9 VS (very susceptible). Exceptions to established ratings do occur unexpectedly as disease situations change.

Greenhouse blast tests are the primary means of screening large number of entries for varietal reaction to the many blast races occurring in the production areas. Although results are quite variable and testing conditions tends to overwhelm any field resistance present in the entry, this test provides an accurate definition of the fungus-variety genetics. Blast field nurseries, utilizing both natural and lab produced inoculum, are established in an effort to better define blast susceptibility under field conditions. Since field nursery is also quite variable, new techniques are currently being developed and evaluated to better estimate cultivar field resistance to blast.

Tables 12 and 13 are summaries of available leaf blast rating data^(a) from CL 181-AR and seven comparison plants inoculated with the indicated race using standard greenhouse techniques.^(b) Data were taken from 2007 to 2008.

For Table 12, column one shows the variety and columns two to nine show leaf blast rating data of each race for each variety.

For Table 13, column one shows the variety name, columns two to three shows the leaf blast rating data, column four shows the panicle blast rating data and column five shows the sheath blight data.

TABLE 12 2008/07 Greenhouse Blast Race Leaf Assays Ave. IB-1 Ave. IB-49 Ave. IC-17 Ave. IE-1 Ave. IG-1 Ave. IH-1 Ave. IE-1k Ave. IB-33 Variety (ZN-15) (ZN-61) (ZN-1) (ZN-6) (ZN-39) (74L2) (ZN-19) (FL9) CL 181-AR 5.5 7.7 7.7 3.7 5.7 0.7 6.7 6.3 S VS VS MR S R S S CL 142-AR 5.8 7.8 8.0 5.0 0.8 0.3 6.3 6.7 S VS VS MS R R S S CL131 0.0 0.0 1.3 0.0 0.3 0.7 4.3 6.3 R R R R R R S S CL161 6.5 8.0 8.0 3.8 1.2 0.7 6.0 7.7 S VS VS MR R R S VS CL171-AR 6.3 7.5 8.0 3.7 0.5 0.0 7.7 7.0 S VS VS MR R R VS S Cybonnet 0.9 0.2 0.7 0.1 0.1 0.0 7.0 6.2 R R R R R R S S Francis 6.5 7.8 7.8 4.7 6.8 1.1 7.3 7.3 S VS VS MS S R VS VS Wells 6.0 7.7 8.1 4.7 2.1 0.1 5.2 7.7 S VS VS MS R R S VS

TABLE 13 2008/07 Field Summary 2008/07 2008 2008/07 PTES PTES PD2* PTES 2008/07 Leaf Blast Leaf Blast Panicle Blast Sheath Blight Variety Average Average Average Average CL 181-AR 4.0 6.5 6.6 7.4 S S-VS S-VS VS CL 142-AR 4.6 7.3 7.2 5.7 S S-VS S-VS MS CL131 1.0 2.3 0.0 8.3 R R R VS CL161 4.3 6.8 5.6 7.3 S S-VS S VS CL171-AR 4.6 7.0 5.9 7.0 S S-VS S-VS S-VS Cybonnet 1.0 3.3 2.5 7.1 R R R S-VS Francis 5.4 7.0 7.0 6.7 S S-VS S-VS S Wells 4.5 6.5 5.5 6.3 S S-VS S S Physiological Evaluations for Rice Cultivar CL 181-AR Straighthead

Straighthead is a physiological disorder which appears to be effected by the oxygen potential of the soil. Under certain conditions, arsenic levels can increase in these soils or on soils where cotton has been grown and MSMA or other arsenical pesticides have been applied. Straighthead may also occur in soils high in organic matter. Symptoms can only be detected after panicle emergence and fail to produce grain. Foliage tends to remain dark green. Rice grains may be distorted especially on long-grain varieties forming a parrot-beak on the end of the hull. Floral parts may also be missing and under severe conditions panicle fail to emerge from the boot.

In Table 14, the reaction of CL 181-AR to Straighthead is compared to various rice cultivars in three separate trials from 2007 and 2008 in Stuttgart, Ark. Column one shows the variety, column two shows the rating from 2007, column three shows the rating from 2008 and column four shows the rating taken as an average from 2007 to 2008.

TABLE 14 Variety 2007² 2008² Average CL 181-AR 3.3 4.0 3.7 CL 142-AR 5.0 5.7 5.4 CL171-AR 5.3 6.0 5.7 CL161 5.3 5.3 5.3 CL131 7.0 — Francis 4.7 4.7 4.7 Wells 6.3 6.7 6.5 LaGrue 6.3 6.0 6.2 Cybonnet 3.7 4.7 4.2 Cocodrie 7.0 7.3 7.2 ¹Based on a scale of 0 to 9 where 0 = no symptoms and 9 = no grain formation. Rating Scale: 0 = no damage 1 = 81-90% grain develop 2 = 71-80% grain develop and 96-100% panicles broken from vertical 3 = 61-80% grain develop and 91-95% panicles broken from vertical 4 = 41-60% grain develop and 61-90% panicles broken from vertical 5 = 21-40% grain develop and 31-60% panicles broken from vertical - initial appearance of parrot-beak distortion 6 = 11-20% grain develop and 10-30% panicles broken from vertical 7 = panicles emerged but totally upright; only 0-10% grain develop 8 = 0-10% panicle emergence, no seed produced 9 = no panicles ²Average of 3 repetitions. Clearfield Disease Evaluations

Tables 15 and 16 provide rough rice grain yield in bushels per acre from 2007 to 2008 from the Disease Monitoring Plots treated with the herbicide NEWPATH, and located in four Arkansas counties.

TABLE 15 2007 Locations Variety Jackson Lincoln Phillips Prairie Mean C.V. CL 181-AR 93 148 158 137 134 21.5 CL 142-AR 100 170 141 137 137 20.9 CL161 91 148 132 123 123 19.7 CL171-AR 100 153 131 115 125 18.5 RT CLXL729 151 192 204 191 185 12.6 RT CLXL730 153 180 144 175 163 10.8 RT CLXP745 150 150 172 170 161 7.6 Mean 96 147 119 125 122 LSD 16 15.7 20.1 16 C.V. 9.8 6.3 9.2 7.2

TABLE 16 2008 Locations Variety Craighead Lincoln Poinsett Mean C.V. CL 181-AR 176 194 190 187 5.0 CL 142-AR 178 206 197 194 7.2 CL131 178 179 160 172 6.0 CL151 172 190 171 178 6.2 CL161 168 196 174 180 8.1 CL171-AR 156 186 166 169 8.9 RT CLXL729 213 223 218 218 2.3 RT CLXL730 182 204 188 192 6.0 RT CLXL745 207 220 190 206 7.1 RT CLXP746 212 220 182 205 9.9 Mean 167 191 183 181 LSD 43.7 19.7 27.4 C.V. 15.8 6.3 9.1

DEPOSIT INFORMATION

A deposit of The Board of Trustees of the University of Arkansas acting for and on behalf of the Division of Agriculture proprietary RICE CULTIVAR CL 181-AR disclosed above and recited in the appended claims has been made with the American Type Culture Collection (ATCC), 10801 University Boulevard, Manassas, Va. 20110. The date of deposit was May 12, 2010. The deposit of 2,500 seeds was taken from the same deposit maintained by The Board of Trustees of the University of Arkansas acting for and on behalf of the Division of Agriculture since prior to the filing date of this application. All restrictions will be irrevocably removed upon granting of a patent, and the deposit is intended to meet all of the requirements of 37 C.F.R. §§1.801-1.809. The ATCC Accession Number is PTA-10948. The deposit will be maintained in the depository for a period of thirty years, or five years after the last request, or for the enforceable life of the patent, whichever is longer, and will be replaced as necessary during that period. 

What is claimed is:
 1. A seed of rice cultivar CL 181-AR, wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 2. A rice plant, or a part thereof, produced by growing the seed of claim
 1. 3. A tissue culture of cells produced from the plant of claim 2, wherein said cells of the tissue culture are produced from a plant part selected from the group consisting of leaves, pollen, embryos, cotyledon, hypocotyl, meristematic cells, roots, root tips, pistils, anthers, flowers, stems, glumes and panicles.
 4. A protoplast produced from the plant of claim
 2. 5. A protoplast produced from the tissue culture of claim
 3. 6. A rice plant regenerated from the tissue culture of claim 3, wherein the plant has all the morphological and physiological characteristics of cultivar CL 181-AR listed in Table
 1. 7. A method for producing an F₁ hybrid rice seed, wherein the method comprises crossing the plant of claim 2 with a different rice plant and harvesting the resultant F₁ hybrid rice seed.
 8. A hybrid rice seed produced by the method of claim
 7. 9. A hybrid rice plant, or a part thereof, produced by growing said hybrid seed of claim
 8. 10. A method of producing an herbicide resistant rice plant, wherein the method comprises transforming the rice plant of claim 2 with a transgene, wherein the transgene confers resistance to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
 11. An herbicide resistant rice plant produced by the method of claim
 10. 12. A method of producing an insect resistant rice plant, wherein the method comprises transforming the rice plant of claim 2 with a transgene that confers insect resistance.
 13. An insect resistant rice plant produced by the method of claim
 12. 14. The rice plant of claim 13, wherein the transgene encodes a Bacillus thuringiensis endotoxin.
 15. A method of producing a disease resistant rice plant, wherein the method comprises transforming the rice plant of claim 2 with a transgene that confers disease resistance.
 16. A disease resistant rice plant produced by the method of claim
 15. 17. A method of producing a rice plant with modified fatty acid metabolism or modified carbohydrate metabolism, wherein the method comprises transforming the rice plant of claim 2 with a transgene encoding a protein selected from the group consisting of fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or DNA encoding an antisense of stearyl-ACP desaturase.
 18. A rice plant having modified fatty acid metabolism or modified carbohydrate metabolism produced by the method of claim
 17. 19. A method of introducing a desired trait into rice cultivar CL 181-AR, wherein the method comprises: (a) crossing a CL 181-AR plant, wherein a representative sample of seed was deposited under ATCC Accession No. PTA-10948, with a plant of another rice cultivar that comprises a desired trait to produce progeny plants wherein the desired trait is selected from the group consisting of male sterility, herbicide resistance, insect resistance, modified fatty acid metabolism, modified carbohydrate metabolism and resistance to bacterial disease, fungal disease or viral disease; (b) selecting one or more progeny plants that have the desired trait; (c) backcrossing the selected progeny plants with the CL 181-AR plants to produce backcross progeny plants; (d) selecting for backcross progeny plants that have the desired trait and all of the physiological and morphological characteristics of rice cultivar CL 181-AR listed in Table 1; and (e) repeating steps (c) and (d) two or more times to produce selected fourth or higher backcross progeny plants that comprise the desired trait and all of the physiological and morphological characteristics of rice cultivar CL 181-AR as listed in Table
 1. 20. A plant produced by the method of claim 19, wherein the plant has the desired trait and all of the physiological and morphological characteristics of rice cultivar CL 181-AR as listed in Table
 1. 21. The plant of claim 20, wherein the desired trait is herbicide resistance and the resistance is conferred to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
 22. The plant of claim 20, wherein the desired trait is insect resistance and the insect resistance is conferred by a transgene encoding a Bacillus thuringiensis endotoxin.
 23. The plant of claim 20, wherein the desired trait is modified fatty acid metabolism or modified carbohydrate metabolism and said desired trait is conferred by a nucleic acid encoding a protein selected from the group consisting of fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or DNA encoding an antisense of stearyl-ACP desaturase.
 24. A method for controlling weeds in the vicinity of a rice plant of rice cultivar CL 181-AR, said method comprising applying an effective amount of at least one acetohydroxyacid synthase (AHAS)-inhibiting herbicide to the weeds and to the rice plant, wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 25. The method of claim 24, wherein said AHAS-inhibiting herbicide is selected from the group consisting of an imidazolinone herbicide, a sulfonylurea herbicide, a triazolopyrimidine herbicide, a pyrimidinyloxybenzoate herbicide, a sulfonylamino-carbonyltriazolinone herbicide, and a mixture thereof.
 26. The method of claim 25, wherein said imidazolinone herbicide is selected from the group consisting of: [2-(4-isopropyl-4-methyl-5-oxo-2-]imidiazolin-2-yl)-nicotinic acid, 2-(4-isopropyl)-4-methyl-5-oxo-2-imidazolin-2-yl)-3-quinolinecarboxylic acid, [5-ethyl-2-(4-isopropyl-4-methyl-]5-oxo-2-imidazolin-2-yl)-nicotinic acid, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-(methoxymethyl)-nicotinic acid, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-methylnicotinic acid, and a mixture of methyl 6-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-m-toluate, methyl[2-(4-]isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate, and a mixture thereof.
 27. The method of claim 24, wherein said AHAS-inhibiting herbicide is an imidazolinone herbicide or a mixture of two or more imidazolinone herbicides.
 28. A seed of rice cultivar CL 181-AR, wherein said seed is treated with an AHAS-inhibiting herbicide, and wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 29. The seed of claim 28, wherein said AHAS-inhibiting herbicide is selected from the group consisting of an imidazolinone herbicide, a sulfonylurea herbicide, a triazolopyrimidine herbicide, a pyrimidinyloxybenzoate herbicide, a sulfonylamino-carbonyltriazolinone herbicide, and a mixture thereof.
 30. The seed of claim 28, wherein said AHAS-inhibiting herbicide is an imidazolinone herbicide or a mixture of two or more imidazolinone herbicides.
 31. A method for combating undesired vegetation comprising contacting a seed of rice cultivar CL 181-AR before sowing and/or after pregermination with an AHAS-inhibiting herbicide, wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 32. The method of claim 31, wherein said AHAS-inhibiting herbicide is selected from the group consisting of an imidazolinone herbicide, a sulfonylurea herbicide, a triazolopyrimidine herbicide, a pyrimidinyloxybenzoate herbicide, a sulfonylamino-carbonyltriazolinone herbicide, and a mixture thereof.
 33. The method of claim 31, wherein said AHAS-inhibiting herbicide is an imidazolinone herbicide or a mixture of two or more imidazolinone herbicides.
 34. A method for producing an herbicide-resistant rice plant, said method comprising crossing a first rice plant that is a rice plant of rice cultivar CL 181-AR with a second rice plant that is not resistant to an herbicide, wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 35. The method of claim 34 further comprising selecting for a progeny rice plant that is resistant to at least one AHAS-inhibiting herbicide.
 36. The method of claim 35, wherein said AHAS-inhibiting herbicide is an imidazolinone herbicide or a mixture of two or more imidazolinone herbicides.
 37. An herbicide-resistant rice plant produced by the method of claim
 34. 38. A method for increasing the herbicide-resistance of a plant, said method comprising crossing a first rice plant that is a rice plant of rice cultivar CL 181-AR with a second rice plant, wherein a representative sample of seed of said cultivar was deposited under ATCC Accession No. PTA-10948.
 39. The method of claim 38 further comprising selecting for a progeny rice plant that comprises increased herbicide resistance to at least one AHAS-inhibiting herbicide when compared to the herbicide resistance of said second rice plant.
 40. The method of claim 39, wherein said AHAS-inhibiting herbicide is an imidazolinone herbicide or a mixture of two or more imidazolinone herbicides.
 41. A plant produced by the method of claim
 38. 